cifs: fix soft mounts hanging in the reconnect code

RHBZ: 1795429

In recent DFS updates we have a new variable controlling how many times we will
retry to reconnect the share.
If DFS is not used, then this variable is initialized to 0 in:

static inline int
dfs_cache_get_nr_tgts(const struct dfs_cache_tgt_list *tl)
{
        return tl ? tl->tl_numtgts : 0;
}

This means that in the reconnect loop in smb2_reconnect() we will immediately wrap retries to -1
and never actually get to pass this conditional:

                if (--retries)
                        continue;

The effect is that we no longer reach the point where we fail the commands with -EHOSTDOWN
and basically the kernel threads are virtually hung and unkillable.

Fixes: a3a53b7 (cifs: Add support for failover in smb2_reconnect())
Signed-off-by: Ronnie Sahlberg <[email protected]>
Signed-off-by: Steve French <[email protected]>
Reviewed-by: Paulo Alcantara (SUSE) <[email protected]>
CC: Stable <[email protected]>

Author: Ronnie Sahlberg

fs/cifs/smb2pdu.c

@@ -312,7 +312,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon)
 		if (server->tcpStatus != CifsNeedReconnect)
 			break;
 
-		if (--retries)
+		if (retries && --retries)
 			continue;
 
 		/*