cifs: fix lease break oops in xfstest generic/098

[ Upstream commit c774e6779f38bf36f0cce65e30793704bab4b0d7 ]

umount can race with lease break so need to check if
tcon->ses->server is still valid to send the lease
break response.

Reviewed-by: Bharath SM <bharathsm@microsoft.com>
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Fixes: 59a556aebc43 ("SMB3: drop reference to cfile before sending oplock break")
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 9a4c33f..87dcffe 100644 (file)
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -5146,9 +5146,13 @@ oplock_break_ack:
         * disconnected since oplock already released by the server
         */
        if (!oplock_break_cancelled) {
-               rc = tcon->ses->server->ops->oplock_response(tcon, persistent_fid,
+               /* check for server null since can race with kill_sb calling tree disconnect */
+               if (tcon->ses && tcon->ses->server) {
+                       rc = tcon->ses->server->ops->oplock_response(tcon, persistent_fid,
                                volatile_fid, net_fid, cinode);
-               cifs_dbg(FYI, "Oplock release rc = %d\n", rc);
+                       cifs_dbg(FYI, "Oplock release rc = %d\n", rc);
+               } else
+                       pr_warn_once("lease break not sent for unmounted share\n");
        }
 
        cifs_done_oplock_break(cinode);