mm: consolidate code to call vm_ops->page_mkwrite()

There are two functions which need to call vm_ops->page_mkwrite():
do_shared_fault() and do_wp_page().  We can consolidate preparation
code.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/memory.c b/mm/memory.c
index d4320e4..ac3990d 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2586,6 +2586,38 @@ static inline void cow_user_page(struct page *dst, struct page *src, unsigned lo
                copy_user_highpage(dst, src, va, vma);
 }
 
+/*
+ * Notify the address space that the page is about to become writable so that
+ * it can prohibit this or wait for the page to get into an appropriate state.
+ *
+ * We do this without the lock held, so that it can sleep if it needs to.
+ */
+static int do_page_mkwrite(struct vm_area_struct *vma, struct page *page,
+              unsigned long address)
+{
+       struct vm_fault vmf;
+       int ret;
+
+       vmf.virtual_address = (void __user *)(address & PAGE_MASK);
+       vmf.pgoff = page->index;
+       vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
+       vmf.page = page;
+
+       ret = vma->vm_ops->page_mkwrite(vma, &vmf);
+       if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
+               return ret;
+       if (unlikely(!(ret & VM_FAULT_LOCKED))) {
+               lock_page(page);
+               if (!page->mapping) {
+                       unlock_page(page);
+                       return 0; /* retry */
+               }
+               ret |= VM_FAULT_LOCKED;
+       } else
+               VM_BUG_ON_PAGE(!PageLocked(page), page);
+       return ret;
+}
+
 /*
  * This routine handles present pages, when users try to write
  * to a shared page. It is done by copying the page to a new address
@@ -2668,42 +2700,15 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
                 * get_user_pages(.write=1, .force=1).
                 */
                if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
-                       struct vm_fault vmf;
                        int tmp;
-
-                       vmf.virtual_address = (void __user *)(address &
-                                                               PAGE_MASK);
-                       vmf.pgoff = old_page->index;
-                       vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
-                       vmf.page = old_page;
-
-                       /*
-                        * Notify the address space that the page is about to
-                        * become writable so that it can prohibit this or wait
-                        * for the page to get into an appropriate state.
-                        *
-                        * We do this without the lock held, so that it can
-                        * sleep if it needs to.
-                        */
                        page_cache_get(old_page);
                        pte_unmap_unlock(page_table, ptl);
-
-                       tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
-                       if (unlikely(tmp &
-                                       (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
-                               ret = tmp;
-                               goto unwritable_page;
+                       tmp = do_page_mkwrite(vma, old_page, address);
+                       if (unlikely(!tmp || (tmp &
+                                       (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
+                               page_cache_release(old_page);
+                               return tmp;
                        }
-                       if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
-                               lock_page(old_page);
-                               if (!old_page->mapping) {
-                                       ret = 0; /* retry the fault */
-                                       unlock_page(old_page);
-                                       goto unwritable_page;
-                               }
-                       } else
-                               VM_BUG_ON_PAGE(!PageLocked(old_page), old_page);
-
                        /*
                         * Since we dropped the lock we need to revalidate
                         * the PTE as someone else may have changed it.  If
@@ -2892,10 +2897,6 @@ oom:
        if (old_page)
                page_cache_release(old_page);
        return VM_FAULT_OOM;
-
-unwritable_page:
-       page_cache_release(old_page);
-       return ret;
 }
 
 static void unmap_mapping_range_vma(struct vm_area_struct *vma,
@@ -3419,7 +3420,6 @@ static int do_shared_fault(struct mm_struct *mm, struct vm_area_struct *vma,
        spinlock_t *ptl;
        pte_t entry, *pte;
        int dirtied = 0;
-       struct vm_fault vmf;
        int ret, tmp;
 
        ret = __do_fault(vma, address, pgoff, flags, &fault_page);
@@ -3430,31 +3430,16 @@ static int do_shared_fault(struct mm_struct *mm, struct vm_area_struct *vma,
         * Check if the backing address space wants to know that the page is
         * about to become writable
         */
-       if (!vma->vm_ops->page_mkwrite)
-               goto set_pte;
-
-       unlock_page(fault_page);
-       vmf.virtual_address = (void __user *)(address & PAGE_MASK);
-       vmf.pgoff = pgoff;
-       vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
-       vmf.page = fault_page;
-
-       tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
-       if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
-               page_cache_release(fault_page);
-               return tmp;
-       }
-
-       if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
-               lock_page(fault_page);
-               if (!fault_page->mapping) {
-                       unlock_page(fault_page);
+       if (vma->vm_ops->page_mkwrite) {
+               unlock_page(fault_page);
+               tmp = do_page_mkwrite(vma, fault_page, address);
+               if (unlikely(!tmp ||
+                               (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
                        page_cache_release(fault_page);
-                       return 0; /* retry */
+                       return tmp;
                }
-       } else
-               VM_BUG_ON_PAGE(!PageLocked(fault_page), fault_page);
-set_pte:
+       }
+
        pte = pte_offset_map_lock(mm, pmd, address, &ptl);
        if (unlikely(!pte_same(*pte, orig_pte))) {
                pte_unmap_unlock(pte, ptl);