[PATCH 3/4] cifs: cifs_pick_channel should skip unhealthy channels

[nspmangalore@gmail.com]

From: Shyam Prasad N <sprasad@microsoft.com>

cifs_pick_channel does not take into account the current
state of the channel today. As a result, if some channels
are unhealthy, they could still get picked, resulting
in unnecessary errors.

This change checks the channel transport status before
making the choice. If all channels are unhealthy, the
primary channel will be returned anyway.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
---
 fs/smb/client/transport.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/fs/smb/client/transport.c b/fs/smb/client/transport.c
index 4f717ad7c21b..f8e6636e90a3 100644
--- a/fs/smb/client/transport.c
+++ b/fs/smb/client/transport.c
@@ -1026,6 +1026,19 @@ struct TCP_Server_Info *cifs_pick_channel(struct cifs_ses *ses)
 		if (!server || server->terminate)
 			continue;
 
+		/*
+		 * do not pick a channel that's not healthy.
+		 * if all channels are unhealthy, we'll use
+		 * the primary channel
+		 */
+		spin_lock(&server->srv_lock);
+		if (server->tcpStatus != CifsNew &&
+		    server->tcpStatus != CifsGood) {
+			spin_unlock(&server->srv_lock);
+			continue;
+		}
+		spin_unlock(&server->srv_lock);
+
 		/*
 		 * strictly speaking, we should pick up req_lock to read
 		 * server->in_flight. But it shouldn't matter much here if we
-- 
2.34.1