[PATCH] cifs: WARN_ON_ONCE if kernel_sendmsg() returns -ENOSPC

[Suresh Jayaraman <sjayaraman-IBi9RG/b67k@public.gmane.org>]

kernel_sendmsg() is less likely to return -ENOSPC and it might be
a bug to do so. However, in the past there might have been cases
where a -ENOSPC was returned from a low level driver.

Add a WARN_ON_ONCE() to ensure that it is safe to assume that -ENOSPC
is no longer returned. This -ENOSPC specific handling will be removed
once we are sure it is no longer returned.

Also, avoid setting -ENOSPC to -EAGAIN while at it.

Cc: Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Signed-off-by: Suresh Jayaraman <sjayaraman-IBi9RG/b67k@public.gmane.org>
---
 fs/cifs/transport.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index d9b639b..afe000f 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -155,6 +155,10 @@ smb_sendv(struct TCP_Server_Info *server, struct kvec *iov, int n_vec)
 		rc = kernel_sendmsg(ssocket, &smb_msg, &iov[first_vec],
 				    n_vec - first_vec, total_len);
 		if ((rc == -ENOSPC) || (rc == -EAGAIN)) {
+			/*
+			 * Catch if a low level driver returns -ENOSPC.
+			 */
+			WARN_ON_ONCE(rc == -ENOSPC);
 			i++;
 			/*
 			 * If blocking send we try 3 times, since each can block
@@ -177,7 +181,6 @@ smb_sendv(struct TCP_Server_Info *server, struct kvec *iov, int n_vec)
 			if ((i >= 14) || (!server->noblocksnd && (i > 2))) {
 				cERROR(1, "sends on sock %p stuck for 15 seconds",
 				    ssocket);
-				rc = -EAGAIN;
 				break;
 			}
 			msleep(1 << i);