From: Patrick Donnelly <pdonnell@redhat.com>
Date: Tue, 25 Feb 2020 18:32:59 +0000 (-0800)
Subject: mds: add comment explaining unusual locking for MDSIOContextBase
X-Git-Tag: v14.2.10~138^2~4
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=983a5010575611ce1ebfa4ba52d303d6894e8dac;p=ceph.git

mds: add comment explaining unusual locking for MDSIOContextBase

Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>
(cherry picked from commit c2a079084c7653b6ed7e0912d4e737fe10a36836)
---

diff --git a/src/mds/MDSContext.cc b/src/mds/MDSContext.cc
index c09e8c3ab566..eecaa81e47e9 100644
--- a/src/mds/MDSContext.cc
+++ b/src/mds/MDSContext.cc
@@ -90,6 +90,9 @@ void MDSIOContextBase::complete(int r) {
 
   dout(10) << "MDSIOContextBase::complete: " << typeid(*this).name() << dendl;
   ceph_assert(mds != NULL);
+  // Note, MDSIOContext is passed outside the MDS and, strangely, we grab the
+  // lock here when MDSContext::complete would otherwise assume the lock is
+  // already acquired.
   std::lock_guard l(mds->mds_lock);
 
   if (mds->is_daemon_stopping()) {