Factor outstanding I/O error handling

Cleanup: setting an outstanding error on a mapping was open coded too many
times.  Factor it out in mapping_set_error().

Signed-off-by: Guillaume Chazarain <guichaz@yahoo.fr>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 029dfad..63cd888 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -683,12 +683,7 @@
 			}
 
 			ret = (*writepage)(page, wbc);
-			if (ret) {
-				if (ret == -ENOSPC)
-					set_bit(AS_ENOSPC, &mapping->flags);
-				else
-					set_bit(AS_EIO, &mapping->flags);
-			}
+			mapping_set_error(mapping, ret);
 
 			if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE))
 				unlock_page(page);