scsi: libiscsi: Reset max/exp cmdsn during recovery

If we lose the session then relogin, but the new cmdsn window has shrunk
(due to something like an admin changing a setting) we will have the old
exp/max_cmdsn values and will never be able to update them. For example,
max_cmdsn would be 64, but if on the target the user set the window to be
smaller then the target could try to return the max_cmdsn as 32. We will
see that new max_cmdsn in the rsp but because it's lower than the old
max_cmdsn when the window was larger we will not update it.

So this patch has us reset the window values during session cleanup so they
can be updated after a new login.

Link: https://lore.kernel.org/r/20210207044608.27585-8-michael.christie@oracle.com
Reviewed-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index f64e2077754c..7ad11e42306d 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -3274,6 +3274,13 @@ int iscsi_conn_bind(struct iscsi_cls_session *cls_session,
 	spin_unlock_bh(&session->frwd_lock);
 
 	/*
+	 * The target could have reduced it's window size between logins, so
+	 * we have to reset max/exp cmdsn so we can see the new values.
+	 */
+	spin_lock_bh(&session->back_lock);
+	session->max_cmdsn = session->exp_cmdsn = session->cmdsn + 1;
+	spin_unlock_bh(&session->back_lock);
+	/*
 	 * Unblock xmitworker(), Login Phase will pass through.
 	 */
 	clear_bit(ISCSI_SUSPEND_BIT, &conn->suspend_rx);