[PATCH 4.18 129/171] NFSv4: Dont exit the state manager without clearing NFS4CLNT_MANAGER_RUNNING

Greg Kroah-Hartman
2018-11-19T16:44:55Z

From: Trond Myklebust <trond.myklebust@hammerspace.com>

commit 21a446cf186570168b7281b154b1993968598aca upstream.

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+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -2553,11 +2553,12 @@ 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 (refcount_read(&clp->cl_count) > 1);
- return;
+ goto out_drain;
+
out_error:
if (strlen(section))
section_sep = ": ";
@@ -2565,6 +2566,7 @@ 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);
}