The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x e7e607bd00481745550389a29ecabe33e13d67cf # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023080733-snowbound-wagon-56bb@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..

Possible dependencies:

e7e607bd0048 ("ceph: defer stopping mdsc delayed_work") 470a5c77eac0 ("ceph: use kill_anon_super helper") fa9967734227 ("ceph: fix potential mdsc use-after-free crash") 3a3430affce5 ("ceph: show tasks waiting on caps in debugfs caps file")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From e7e607bd00481745550389a29ecabe33e13d67cf Mon Sep 17 00:00:00 2001 From: Xiubo Li xiubli@redhat.com Date: Tue, 25 Jul 2023 12:03:59 +0800 Subject: [PATCH] ceph: defer stopping mdsc delayed_work

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@vger.kernel.org Link: https://tracker.ceph.com/issues/61843 Signed-off-by: Xiubo Li xiubli@redhat.com Reviewed-by: Milind Changire mchangir@redhat.com Signed-off-by: Ilya Dryomov idryomov@gmail.com

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c index 66048a86c480..5fb367b1d4b0 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -4764,7 +4764,7 @@ 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); @@ -4943,7 +4943,7 @@ void send_flush_mdlog(struct ceph_mds_session *s) void ceph_mdsc_pre_umount(struct ceph_mds_client *mdsc) { dout("pre_umount\n"); - mdsc->stopping = 1; + mdsc->stopping = CEPH_MDSC_STOPPING_BEGIN;

ceph_mdsc_iterate_sessions(mdsc, send_flush_mdlog, true); ceph_mdsc_iterate_sessions(mdsc, lock_unlock_session, false); diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h index 724307ff89cd..86d2965e68a1 100644 --- a/fs/ceph/mds_client.h +++ b/fs/ceph/mds_client.h @@ -380,6 +380,11 @@ 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 3fc48b43cab0..a5f52013314d 100644 --- a/fs/ceph/super.c +++ b/fs/ceph/super.c @@ -1374,6 +1374,16 @@ 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;