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authorMichel Lespinasse <walken@google.com>2011-01-13 15:46:08 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2011-01-13 17:32:35 -0800
commit72ddc8f72270758951ccefb7d190f364d20215ab (patch)
tree11772272825f72aa3f32c0f9be5cf35155cf1441 /mm/memory.c
parentb009c024ff0059e293c1937516f2defe56263650 (diff)
do_wp_page: clarify dirty_page handling
Reorganize the code so that dirty pages are handled closer to the place that makes them dirty (handling write fault into shared, writable VMAs). No behavior changes. Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Kosaki Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Theodore Tso <tytso@google.com> Cc: Michael Rubin <mrubin@google.com> Cc: Suleiman Souhlal <suleiman@google.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memory.c')
-rw-r--r--mm/memory.c72
1 files changed, 38 insertions, 34 deletions
diff --git a/mm/memory.c b/mm/memory.c
index d0cc1c134a6..9144fae9a68 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2229,8 +2229,45 @@ reuse:
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
if (ptep_set_access_flags(vma, address, page_table, entry,1))
update_mmu_cache(vma, address, page_table);
+ pte_unmap_unlock(page_table, ptl);
ret |= VM_FAULT_WRITE;
- goto unlock;
+
+ if (!dirty_page)
+ return ret;
+
+ /*
+ * Yes, Virginia, this is actually required to prevent a race
+ * with clear_page_dirty_for_io() from clearing the page dirty
+ * bit after it clear all dirty ptes, but before a racing
+ * do_wp_page installs a dirty pte.
+ *
+ * do_no_page is protected similarly.
+ */
+ if (!page_mkwrite) {
+ wait_on_page_locked(dirty_page);
+ set_page_dirty_balance(dirty_page, page_mkwrite);
+ }
+ put_page(dirty_page);
+ if (page_mkwrite) {
+ struct address_space *mapping = dirty_page->mapping;
+
+ set_page_dirty(dirty_page);
+ unlock_page(dirty_page);
+ page_cache_release(dirty_page);
+ if (mapping) {
+ /*
+ * Some device drivers do not set page.mapping
+ * but still dirty their pages
+ */
+ balance_dirty_pages_ratelimited(mapping);
+ }
+ }
+
+ /* file_update_time outside page_lock */
+ if (vma->vm_file)
+ file_update_time(vma->vm_file);
+
+ return ret;
}
/*
@@ -2336,39 +2373,6 @@ gotten:
page_cache_release(old_page);
unlock:
pte_unmap_unlock(page_table, ptl);
- if (dirty_page) {
- /*
- * Yes, Virginia, this is actually required to prevent a race
- * with clear_page_dirty_for_io() from clearing the page dirty
- * bit after it clear all dirty ptes, but before a racing
- * do_wp_page installs a dirty pte.
- *
- * do_no_page is protected similarly.
- */
- if (!page_mkwrite) {
- wait_on_page_locked(dirty_page);
- set_page_dirty_balance(dirty_page, page_mkwrite);
- }
- put_page(dirty_page);
- if (page_mkwrite) {
- struct address_space *mapping = dirty_page->mapping;
-
- set_page_dirty(dirty_page);
- unlock_page(dirty_page);
- page_cache_release(dirty_page);
- if (mapping) {
- /*
- * Some device drivers do not set page.mapping
- * but still dirty their pages
- */
- balance_dirty_pages_ratelimited(mapping);
- }
- }
-
- /* file_update_time outside page_lock */
- if (vma->vm_file)
- file_update_time(vma->vm_file);
- }
return ret;
oom_free_new:
page_cache_release(new_page);