cifs: add ignore_pend flag to cifs_call_async

The current code always ignores the max_pending limit. Have it instead
only optionally ignore the pending limit. For CIFSSMBEcho, we need to
ignore it to make sure they always can go out. For async reads, writes
and potentially other calls, we need to respect it.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

fs/cifs/cifsproto.h

@@ -69,7 +69,7 @@ extern struct mid_q_entry *AllocMidQEntry(const struct smb_hdr *smb_buffer,
 extern void DeleteMidQEntry(struct mid_q_entry *midEntry);
 extern int cifs_call_async(struct TCP_Server_Info *server, struct kvec *iov,
 			   unsigned int nvec, mid_callback_t *callback,
-			   void *cbdata);
+			   void *cbdata, bool ignore_pend);
 extern int SendReceive(const unsigned int /* xid */ , struct cifsSesInfo *,
 			struct smb_hdr * /* input */ ,
 			struct smb_hdr * /* out */ ,

fs/cifs/cifssmb.c

@@ -743,7 +743,7 @@ CIFSSMBEcho(struct TCP_Server_Info *server)
 	iov.iov_base = smb;
 	iov.iov_len = be32_to_cpu(smb->hdr.smb_buf_length) + 4;
 
-	rc = cifs_call_async(server, &iov, 1, cifs_echo_callback, server);
+	rc = cifs_call_async(server, &iov, 1, cifs_echo_callback, server, true);
 	if (rc)
 		cFYI(1, "Echo request failed: %d", rc);
 

fs/cifs/transport.c

@@ -343,13 +343,14 @@ wait_for_response(struct TCP_Server_Info *server, struct mid_q_entry *midQ)
  */
 int
 cifs_call_async(struct TCP_Server_Info *server, struct kvec *iov,
-		unsigned int nvec, mid_callback_t *callback, void *cbdata)
+		unsigned int nvec, mid_callback_t *callback, void *cbdata,
+		bool ignore_pend)
 {
 	int rc;
 	struct mid_q_entry *mid;
 	struct smb_hdr *hdr = (struct smb_hdr *)iov[0].iov_base;
 
-	rc = wait_for_free_request(server, CIFS_ASYNC_OP);
+	rc = wait_for_free_request(server, ignore_pend ? CIFS_ASYNC_OP : 0);
 	if (rc)
 		return rc;