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: Ifdd5e09defcf0705901ff7f23001d68a811da3af
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
(cherry picked from commit 1ccd6c4ff9ccd74bb87903067618815d326af242)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 1afce941..c9db73e 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1905,7 +1905,13 @@
 
 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;