From: Trond Myklebust <trond.myklebust@hammerspace.com>
Date: Mon, 5 Nov 2018 11:10:50 -0500
Subject: [PATCH] NFSv4: Don't exit the state manager without clearing
 NFS4CLNT_MANAGER_RUNNING
Git-commit: 21a446cf186570168b7281b154b1993968598aca
Patch-mainline: v4.20
References: git-fixes

If we exit the NFSv4 state manager due to a umount, then we can end up
leaving the NFS4CLNT_MANAGER_RUNNING flag set. If another mount causes
the nfs4_client to be rereferenced before it is destroyed, then we end
up never being able to recover state.

Fixes: 47c2199b6eb5 ("NFSv4.1: Ensure state manager thread dies on last ...")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: stable@vger.kernel.org # v4.15+
Acked-by: NeilBrown <neilb@suse.com>

---
 fs/nfs/nfs4state.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -2508,11 +2508,12 @@ static void nfs4_state_manager(struct nf
 		nfs4_clear_state_manager_bit(clp);
 		/* Did we race with an attempt to give us more work? */
 		if (clp->cl_state == 0)
-			break;
+			return;
 		if (test_and_set_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state) != 0)
-			break;
+			return;
 	} while (atomic_read(&clp->cl_count) > 1);
-	return;
+	goto out_drain;
+
 out_error:
 	if (strlen(section))
 		section_sep = ": ";
@@ -2520,6 +2521,7 @@ out_error:
 			" with error %d\n", section_sep, section,
 			clp->cl_hostname, -status);
 	ssleep(1);
+out_drain:
 	nfs4_end_drain_session(clp);
 	nfs4_clear_state_manager_bit(clp);
 }