From: chungfengz <chungfengz@synology.com>
Date: Thu, 16 Apr 2026 06:54:16 +0000 (+0000)
Subject: mds: fix shutdown hang when ephemeral pins active and max_mds is 0
X-Git-Tag: v21.0.1~26^2
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=refs%2Fpull%2F68413%2Fhead;p=ceph.git

mds: fix shutdown hang when ephemeral pins active and max_mds is 0

During shutdown, `ceph fs set <fs> down true` sets max_mds to 0 before
the MDS daemons have finished exporting their subtrees.  shutdown_pass()
iterates over auth subtrees and skips any dir whose inode is
ephemerally pinned, expecting handle_export_pins() to re-place them.
However, handle_export_pins() calls hash_into_rank_bucket() which (after
the companion fix) now returns MDS_RANK_NONE when max_mds == 0.  With
no valid target rank the export is never scheduled, so the ephemerally-
pinned dirs are skipped by shutdown_pass() indefinitely and the daemon
loops.

Fixes: https://tracker.ceph.com/issues/76059
Signed-off-by: chungfengz <chungfengz@synology.com>
---

diff --git a/src/mds/MDCache.cc b/src/mds/MDCache.cc
index 268f7122069..521ed40a109 100644
--- a/src/mds/MDCache.cc
+++ b/src/mds/MDCache.cc
@@ -8018,7 +8018,8 @@ bool MDCache::shutdown_pass()
           dir->is_freezing() ||
           dir->is_ambiguous_dir_auth() ||
           dir->state_test(CDir::STATE_EXPORTING) ||
-          dir->get_inode()->is_ephemerally_pinned()) {
+          (mds->mdsmap->get_max_mds() > 0 &&
+           dir->get_inode()->is_ephemerally_pinned())) {
         continue;
       }
       ls.push_back(dir);