Patch "ceph: defer stopping mdsc delayed_work" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    ceph: defer stopping mdsc delayed_work

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ceph-defer-stopping-mdsc-delayed_work.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 1b955d8f1e8b096b446555103934705d1052f63e
Author: Xiubo Li <xiubli@xxxxxxxxxx>
Date:   Tue Jul 25 12:03:59 2023 +0800

    ceph: defer stopping mdsc delayed_work
    
    [ Upstream commit e7e607bd00481745550389a29ecabe33e13d67cf ]
    
    Flushing the dirty buffer may take a long time if the cluster is
    overloaded or if there is network issue. So we should ping the
    MDSs periodically to keep alive, else the MDS will blocklist
    the kclient.
    
    Cc: stable@xxxxxxxxxxxxxxx
    Link: https://tracker.ceph.com/issues/61843
    Signed-off-by: Xiubo Li <xiubli@xxxxxxxxxx>
    Reviewed-by: Milind Changire <mchangir@xxxxxxxxxx>
    Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 6ceda2a4791c4..f7acf9680c9b6 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -4074,7 +4074,7 @@ static void delayed_work(struct work_struct *work)
 
 	dout("mdsc delayed_work\n");
 
-	if (mdsc->stopping)
+	if (mdsc->stopping >= CEPH_MDSC_STOPPING_FLUSHED)
 		return;
 
 	mutex_lock(&mdsc->mutex);
@@ -4246,7 +4246,7 @@ static void wait_requests(struct ceph_mds_client *mdsc)
 void ceph_mdsc_pre_umount(struct ceph_mds_client *mdsc)
 {
 	dout("pre_umount\n");
-	mdsc->stopping = 1;
+	mdsc->stopping = CEPH_MDSC_STOPPING_BEGIN;
 
 	lock_unlock_sessions(mdsc);
 	ceph_flush_dirty_caps(mdsc);
diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
index 14c7e8c49970a..4fbbc33023c97 100644
--- a/fs/ceph/mds_client.h
+++ b/fs/ceph/mds_client.h
@@ -348,6 +348,11 @@ struct cap_wait {
 	int			want;
 };
 
+enum {
+       CEPH_MDSC_STOPPING_BEGIN = 1,
+       CEPH_MDSC_STOPPING_FLUSHED = 2,
+};
+
 /*
  * mds client state
  */
diff --git a/fs/ceph/super.c b/fs/ceph/super.c
index 279334f955702..0e38678d5adda 100644
--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -1180,6 +1180,16 @@ static void ceph_kill_sb(struct super_block *s)
 	ceph_mdsc_pre_umount(fsc->mdsc);
 	flush_fs_workqueues(fsc);
 
+	/*
+	 * Though the kill_anon_super() will finally trigger the
+	 * sync_filesystem() anyway, we still need to do it here
+	 * and then bump the stage of shutdown to stop the work
+	 * queue as earlier as possible.
+	 */
+	sync_filesystem(s);
+
+	fsc->mdsc->stopping = CEPH_MDSC_STOPPING_FLUSHED;
+
 	kill_anon_super(s);
 
 	fsc->client->extra_mon_dispatch = NULL;