[PATCH 5.15 863/917] ceph: fix mdsmap decode when there are MDSs beyond max_mds

Greg Kroah-Hartman
2021-11-16T00:02:38Z

From: Xiubo Li <xiubli@redhat.com>

commit 0e24421ac431e7af62d4acef6c638b85aae51728 upstream.

If the max_mds is decreased in a cephfs cluster, there is a window
of time before the MDSs are removed. If a map goes out during this
period, the mdsmap may show the decreased max_mds but still shows
those MDSes as in or in the export target list.

Ensure that we don't fail the map decode in that case.

Cc: stable@vger.kernel.org
URL: https://tracker.ceph.com/issues/52436
Fixes: d517b3983dd3 ("ceph: reconnect to the export targets on new mdsmaps")
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/ceph/mdsmap.c | 4 ----
1 file changed, 4 deletions(-)

--- a/fs/ceph/mdsmap.c
+++ b/fs/ceph/mdsmap.c
@@ -263,10 +263,6 @@ struct ceph_mdsmap *ceph_mdsmap_decode(v
goto nomem;
for (j = 0; j < num_export_targets; j++) {
target = ceph_decode_32(&pexport_targets);
- if (target >= m->possible_max_rank) {
- err = -EIO;
- goto corrupt;
- }
info->export_targets[j] = target;
}
} else {