From: Yanhu Cao <gmayyyha@gmail.com>
Date: Fri, 31 Jul 2020 16:25:13 +0800
Subject: ceph: use frag's MDS in either mode
Git-commit: 224c7b6778fe08e1880ef88867051bec0a154d6c
Patch-mainline: v5.9-rc1
References: bsc#1176542

When doing some tests with multiple mds, we were seeing many mds
forwarding requests between them, causing clients to resend.

If the request is a modification operation and the mode is set to
USE_AUTH_MDS, then the auth mds should be selected to handle the
request. If auth mds for frag is already set, then it should be returned
directly without further processing.

The current logic is wrong because it only returns directly if
mode is USE_AUTH_MDS, but we want to do that for all modes. If we don't,
then when the frag's mds is not equal to cap session's mds, the request
will get sent to the wrong MDS needlessly.

Drop the mode check in this condition.

Signed-off-by: Yanhu Cao <gmayyyha@gmail.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Acked-by: Luis Henriques <lhenriques@suse.com>
---
 fs/ceph/mds_client.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 590822fab767..1095802ad9bd 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -1103,8 +1103,7 @@ static int __choose_mds(struct ceph_mds_client *mdsc,
 				     frag.frag, mds);
 				if (ceph_mdsmap_get_state(mdsc->mdsmap, mds) >=
 				    CEPH_MDS_STATE_ACTIVE) {
-					if (mode == USE_ANY_MDS &&
-					    !ceph_mdsmap_is_laggy(mdsc->mdsmap,
+					if (!ceph_mdsmap_is_laggy(mdsc->mdsmap,
 								  mds))
 						goto out;
 				}