UPSTREAM: f2fs: avoid fsync() failure caused by EAGAIN in writepage()

pageout() in MM traslates EAGAIN, so calls handle_write_error()
 -> mapping_set_error() -> set_bit(AS_EIO, ...).
 file_write_and_wait_range() will see EIO error, which is critical
 to return value of fsync() followed by atomic_write failure to user.

Change-Id: I6124ed299baf5e5b8993bb6b54f07bb8771eda8c
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
(cherry picked from commit 520a948)

Author: Jaegeuk Kim

fs/f2fs/data.c

@@ -1902,7 +1902,13 @@ static int __write_data_page(struct page *page, bool *submitted,
 
 redirty_out:
 	redirty_page_for_writepage(wbc, page);
-	if (!err)
+	/*
+	 * pageout() in MM traslates EAGAIN, so calls handle_write_error()
+	 * -> mapping_set_error() -> set_bit(AS_EIO, ...).
+	 * file_write_and_wait_range() will see EIO error, which is critical
+	 * to return value of fsync() followed by atomic_write failure to user.
+	 */
+	if (!err || wbc->for_reclaim)
 		return AOP_WRITEPAGE_ACTIVATE;
 	unlock_page(page);
 	return err;