The do_wp_page function is extremely long. Extract the logic for
handling a page belonging to a shared vma into a function of its own.
This helps the readability of the code, without doing any functional
change in it.
Signed-off-by: Shachar Raindel <raindel@xxxxxxxxxxxx>
---
mm/memory.c | 86 ++++++++++++++++++++++++++++++++++---------------------------
1 file changed, 48 insertions(+), 38 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c
index c7c0df2..e730628 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2227,6 +2227,52 @@ oom:
return VM_FAULT_OOM;
}
+static int wp_page_shared(struct mm_struct *mm, struct vm_area_struct *vma,
+ unsigned long address, pte_t *page_table,
+ pmd_t *pmd, spinlock_t *ptl, pte_t orig_pte,
+ struct page *old_page)
+ __releases(ptl)
+{
+ int page_mkwrite = 0;
+ int ret;
+
+ /*
+ * Only catch write-faults on shared writable pages, read-only shared
+ * pages can get COWed by get_user_pages(.write=1, .force=1).
+ */
+ if (!vma->vm_ops || !vma->vm_ops->page_mkwrite)
+ goto no_mkwrite;
+
+ page_cache_get(old_page);
+ pte_unmap_unlock(page_table, ptl);
+ ret = do_page_mkwrite(vma, old_page, address);
+ if (unlikely(!ret || (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
+ page_cache_release(old_page);
+ return ret;
+ }
+ /*
+ * Since we dropped the lock we need to revalidate
+ * the PTE as someone else may have changed it. If
+ * they did, we just return, as we can count on the
+ * MMU to tell us if they didn't also make it writable.
+ */
+ page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
+ if (!pte_same(*page_table, orig_pte)) {
+ unlock_page(old_page);
+ pte_unmap_unlock(page_table, ptl);
+ page_cache_release(old_page);
+ return 0;
+ }
+
+ page_mkwrite = 1;
+
+no_mkwrite:
+ get_page(old_page);
+
+ return wp_page_reuse(mm, vma, address, page_table, ptl, orig_pte,
+ old_page, 1, page_mkwrite);
+}
+
/*
* 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
@@ -2305,44 +2351,8 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
unlock_page(old_page);
} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
(VM_WRITE|VM_SHARED))) {
- int page_mkwrite = 0;
-
- /*
- * Only catch write-faults on shared writable pages,
- * read-only shared pages can get COWed by
- * get_user_pages(.write=1, .force=1).
- */
- if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
- int tmp;
- page_cache_get(old_page);
- pte_unmap_unlock(page_table, ptl);
- 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;
- }
- /*
- * Since we dropped the lock we need to revalidate
- * the PTE as someone else may have changed it. If
- * they did, we just return, as we can count on the
- * MMU to tell us if they didn't also make it writable.
- */
- page_table = pte_offset_map_lock(mm, pmd, address,
- &ptl);
- if (!pte_same(*page_table, orig_pte)) {
- unlock_page(old_page);
- pte_unmap_unlock(page_table, ptl);
- page_cache_release(old_page);
- return 0;
- }
-
- page_mkwrite = 1;
- }
- get_page(old_page);
-
- return wp_page_reuse(mm, vma, address, page_table, ptl,
- orig_pte, old_page, 1, page_mkwrite);
+ return wp_page_shared(mm, vma, address, page_table, pmd,
+ ptl, orig_pte, old_page);
}
/*
--
1.7.11.2
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