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-rw-r--r--fs/cifs/smb2glob.h10
-rw-r--r--fs/cifs/smb2pdu.c18
2 files changed, 27 insertions, 1 deletions
diff --git a/fs/cifs/smb2glob.h b/fs/cifs/smb2glob.h
index 0ffa18094335..238759c146ba 100644
--- a/fs/cifs/smb2glob.h
+++ b/fs/cifs/smb2glob.h
@@ -61,4 +61,14 @@
 /* Maximum buffer size value we can send with 1 credit */
 #define SMB2_MAX_BUFFER_SIZE 65536
 
+/*
+ * Maximum number of credits to keep available.
+ * This value is chosen somewhat arbitrarily. The Windows client
+ * defaults to 128 credits, the Windows server allows clients up to
+ * 512 credits, and the NetApp server does not limit clients at all.
+ * Choose a high enough value such that the client shouldn't limit
+ * performance.
+ */
+#define SMB2_MAX_CREDITS_AVAILABLE 32000
+
 #endif	/* _SMB2_GLOB_H */
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 29e06db5f187..967a7904fb8f 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -100,7 +100,21 @@ smb2_hdr_assemble(struct smb2_hdr *hdr, __le16 smb2_cmd /* command */ ,
 	hdr->ProtocolId = SMB2_PROTO_NUMBER;
 	hdr->StructureSize = cpu_to_le16(64);
 	hdr->Command = smb2_cmd;
-	hdr->CreditRequest = cpu_to_le16(2); /* BB make this dynamic */
+	if (tcon && tcon->ses && tcon->ses->server) {
+		struct TCP_Server_Info *server = tcon->ses->server;
+
+		spin_lock(&server->req_lock);
+		/* Request up to 2 credits but don't go over the limit. */
+		if (server->credits >= SMB2_MAX_CREDITS_AVAILABLE)
+			hdr->CreditRequest = cpu_to_le16(0);
+		else
+			hdr->CreditRequest = cpu_to_le16(
+				min_t(int, SMB2_MAX_CREDITS_AVAILABLE -
+						server->credits, 2));
+		spin_unlock(&server->req_lock);
+	} else {
+		hdr->CreditRequest = cpu_to_le16(2);
+	}
 	hdr->ProcessId = cpu_to_le32((__u16)current->tgid);
 
 	if (!tcon)
@@ -2057,6 +2071,7 @@ smb2_async_readv(struct cifs_readdata *rdata)
 	if (rdata->credits) {
 		buf->CreditCharge = cpu_to_le16(DIV_ROUND_UP(rdata->bytes,
 						SMB2_MAX_BUFFER_SIZE));
+		buf->CreditRequest = buf->CreditCharge;
 		spin_lock(&server->req_lock);
 		server->credits += rdata->credits -
 						le16_to_cpu(buf->CreditCharge);
@@ -2243,6 +2258,7 @@ smb2_async_writev(struct cifs_writedata *wdata,
 	if (wdata->credits) {
 		req->hdr.CreditCharge = cpu_to_le16(DIV_ROUND_UP(wdata->bytes,
 						    SMB2_MAX_BUFFER_SIZE));
+		req->hdr.CreditRequest = req->hdr.CreditCharge;
 		spin_lock(&server->req_lock);
 		server->credits += wdata->credits -
 					le16_to_cpu(req->hdr.CreditCharge);