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: I1e1048eb271a58ddcb8a3050922d9e883aa0252c
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
(cherry picked from commit 8c088f40561cb73b8226ef975e66b5285c8943df)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 18233dc..e2e560e 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1886,7 +1886,13 @@
 
 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;