CIFS: Add SMB2 credits support

For SMB2 protocol we can add more than one credit for one received
request: it depends on CreditRequest field in SMB2 response header.
Also we divide all requests by type: echoes, oplocks and others.
Each type uses its own slot pull.

Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Pavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: Steve French <smfrench@gmail.com>

1 files changed, 79 insertions, 0 deletions

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 09530f416123..67a05984cd41 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -20,6 +20,81 @@
 #include "cifsglob.h"
 #include "smb2pdu.h"
 #include "smb2proto.h"
+#include "cifsproto.h"
+#include "cifs_debug.h"
+
+static int
+change_conf(struct TCP_Server_Info *server)
+{
+        server->credits += server->echo_credits + server->oplock_credits;
+        server->oplock_credits = server->echo_credits = 0;
+        switch (server->credits) {
+        case 0:
+                return -1;
+        case 1:
+                server->echoes = false;
+                server->oplocks = false;
+                cERROR(1, "disabling echoes and oplocks");
+                break;
+        case 2:
+                server->echoes = true;
+                server->oplocks = false;
+                server->echo_credits = 1;
+                cFYI(1, "disabling oplocks");
+                break;
+        default:
+                server->echoes = true;
+                server->oplocks = true;
+                server->echo_credits = 1;
+                server->oplock_credits = 1;
+        }
+        server->credits -= server->echo_credits + server->oplock_credits;
+        return 0;
+}
+
+static void
+smb2_add_credits(struct TCP_Server_Info *server, const unsigned int add,
+                 const int optype)
+{
+        int *val, rc = 0;
+        spin_lock(&server->req_lock);
+        val = server->ops->get_credits_field(server, optype);
+        *val += add;
+        server->in_flight--;
+        if (server->in_flight == 0)
+                rc = change_conf(server);
+        spin_unlock(&server->req_lock);
+        wake_up(&server->request_q);
+        if (rc)
+                cifs_reconnect(server);
+}
+
+static void
+smb2_set_credits(struct TCP_Server_Info *server, const int val)
+{
+        spin_lock(&server->req_lock);
+        server->credits = val;
+        spin_unlock(&server->req_lock);
+}
+
+static int *
+smb2_get_credits_field(struct TCP_Server_Info *server, const int optype)
+{
+        switch (optype) {
+        case CIFS_ECHO_OP:
+                return &server->echo_credits;
+        case CIFS_OBREAK_OP:
+                return &server->oplock_credits;
+        default:
+                return &server->credits;
+        }
+}
+
+static unsigned int
+smb2_get_credits(struct mid_q_entry *mid)
+{
+        return le16_to_cpu(((struct smb2_hdr *)mid->resp_buf)->CreditRequest);
+}
 
 static __u64
 smb2_get_next_mid(struct TCP_Server_Info *server)
@@ -35,6 +110,10 @@ smb2_get_next_mid(struct TCP_Server_Info *server)
 struct smb_version_operations smb21_operations = {
         .setup_request = smb2_setup_request,
         .check_receive = smb2_check_receive,
+        .add_credits = smb2_add_credits,
+        .set_credits = smb2_set_credits,
+        .get_credits_field = smb2_get_credits_field,
+        .get_credits = smb2_get_credits,
         .get_next_mid = smb2_get_next_mid,
 };