CIFS: Simplify socket reading in demultiplex thread
Pavel Shilovsky [Mon, 1 Aug 2011 09:19:41 +0000 (13:19 +0400)]
Move reading to separate function and remove csocket variable.

Also change semantic in a little: goto incomplete_rcv only when
we get -EAGAIN (or a familiar error) while reading rfc1002 header.
In this case we don't check for echo timeout when we don't get whole
header at once, as it was before.

Reviewed-and-Tested-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Pavel Shilovsky <piastryyy@gmail.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

fs/cifs/connect.c

index 217d365..a2e9fcf 100644 (file)
@@ -359,6 +359,64 @@ allocate_buffers(char **bigbuf, char **smallbuf, unsigned int size,
 }
 
 static int
+read_from_socket(struct TCP_Server_Info *server, struct msghdr *smb_msg,
+                struct kvec *iov, unsigned int to_read,
+                unsigned int *ptotal_read, bool is_header_read)
+{
+       int length, rc = 0;
+       unsigned int total_read;
+       char *buf = iov->iov_base;
+
+       for (total_read = 0; total_read < to_read; total_read += length) {
+               length = kernel_recvmsg(server->ssocket, smb_msg, iov, 1,
+                                       to_read - total_read, 0);
+               if (server->tcpStatus == CifsExiting) {
+                       /* then will exit */
+                       rc = 2;
+                       break;
+               } else if (server->tcpStatus == CifsNeedReconnect) {
+                       cifs_reconnect(server);
+                       /* Reconnect wakes up rspns q */
+                       /* Now we will reread sock */
+                       rc = 1;
+                       break;
+               } else if (length == -ERESTARTSYS ||
+                          length == -EAGAIN ||
+                          length == -EINTR) {
+                       /*
+                        * Minimum sleep to prevent looping, allowing socket
+                        * to clear and app threads to set tcpStatus
+                        * CifsNeedReconnect if server hung.
+                        */
+                       usleep_range(1000, 2000);
+                       length = 0;
+                       if (!is_header_read)
+                               continue;
+                       /* Special handling for header read */
+                       if (total_read) {
+                               iov->iov_base = (to_read - total_read) +
+                                               buf;
+                               iov->iov_len = to_read - total_read;
+                               smb_msg->msg_control = NULL;
+                               smb_msg->msg_controllen = 0;
+                               rc = 3;
+                       } else
+                               rc = 1;
+                       break;
+               } else if (length <= 0) {
+                       cERROR(1, "Received no data, expecting %d",
+                              to_read - total_read);
+                       cifs_reconnect(server);
+                       rc = 1;
+                       break;
+               }
+       }
+
+       *ptotal_read = total_read;
+       return rc;
+}
+
+static int
 cifs_demultiplex_thread(void *p)
 {
        int length;
@@ -368,14 +426,13 @@ cifs_demultiplex_thread(void *p)
        struct smb_hdr *smb_buffer = NULL;
        struct msghdr smb_msg;
        struct kvec iov;
-       struct socket *csocket = server->ssocket;
        struct list_head *tmp, *tmp2;
        struct task_struct *task_to_wake = NULL;
        struct mid_q_entry *mid_entry;
        char temp;
        bool isLargeBuf = false;
        bool isMultiRsp;
-       int reconnect;
+       int rc;
 
        current->flags |= PF_MEMALLOC;
        cFYI(1, "Demultiplex PID: %d", task_pid_nr(current));
@@ -412,51 +469,18 @@ incomplete_rcv:
                                  "Reconnecting...", server->hostname,
                                  (echo_retries * SMB_ECHO_INTERVAL / HZ));
                        cifs_reconnect(server);
-                       csocket = server->ssocket;
                        wake_up(&server->response_q);
                        continue;
                }
 
-               length =
-                   kernel_recvmsg(csocket, &smb_msg,
-                               &iov, 1, pdu_length, 0 /* BB other flags? */);
-
-               if (server->tcpStatus == CifsExiting) {
+               rc = read_from_socket(server, &smb_msg, &iov, pdu_length,
+                                     &total_read, true /* header read */);
+               if (rc == 3)
+                       goto incomplete_rcv;
+               else if (rc == 2)
                        break;
-               } else if (server->tcpStatus == CifsNeedReconnect) {
-                       cFYI(1, "Reconnect after server stopped responding");
-                       cifs_reconnect(server);
-                       cFYI(1, "call to reconnect done");
-                       csocket = server->ssocket;
-                       continue;
-               } else if (length == -ERESTARTSYS ||
-                          length == -EAGAIN ||
-                          length == -EINTR) {
-                       msleep(1); /* minimum sleep to prevent looping
-                               allowing socket to clear and app threads to set
-                               tcpStatus CifsNeedReconnect if server hung */
-                       if (pdu_length < 4) {
-                               iov.iov_base = (4 - pdu_length) + buf;
-                               iov.iov_len = pdu_length;
-                               smb_msg.msg_control = NULL;
-                               smb_msg.msg_controllen = 0;
-                               goto incomplete_rcv;
-                       } else
-                               continue;
-               } else if (length <= 0) {
-                       cFYI(1, "Reconnect after unexpected peek error %d",
-                               length);
-                       cifs_reconnect(server);
-                       csocket = server->ssocket;
-                       wake_up(&server->response_q);
+               else if (rc == 1)
                        continue;
-               } else if (length < pdu_length) {
-                       cFYI(1, "requested %d bytes but only got %d bytes",
-                                 pdu_length, length);
-                       pdu_length -= length;
-                       msleep(1);
-                       goto incomplete_rcv;
-               }
 
                /* The right amount was read from socket - 4 bytes */
                /* so we can now interpret the length field */
@@ -493,14 +517,12 @@ incomplete_rcv:
                        cifs_set_port((struct sockaddr *)
                                        &server->dstaddr, CIFS_PORT);
                        cifs_reconnect(server);
-                       csocket = server->ssocket;
                        wake_up(&server->response_q);
                        continue;
                } else if (temp != (char) 0) {
                        cERROR(1, "Unknown RFC 1002 frame");
                        cifs_dump_mem(" Received Data: ", buf, length);
                        cifs_reconnect(server);
-                       csocket = server->ssocket;
                        continue;
                }
 
@@ -510,59 +532,25 @@ incomplete_rcv:
                        cERROR(1, "Invalid size SMB length %d pdu_length %d",
                                        length, pdu_length+4);
                        cifs_reconnect(server);
-                       csocket = server->ssocket;
                        wake_up(&server->response_q);
                        continue;
                }
 
                /* else length ok */
-               reconnect = 0;
-
                if (pdu_length > MAX_CIFS_SMALL_BUFFER_SIZE - 4) {
                        isLargeBuf = true;
                        memcpy(bigbuf, smallbuf, 4);
                        smb_buffer = (struct smb_hdr *)bigbuf;
                        buf = bigbuf;
                }
-               length = 0;
+
                iov.iov_base = 4 + buf;
                iov.iov_len = pdu_length;
-               for (total_read = 0; total_read < pdu_length;
-                    total_read += length) {
-                       length = kernel_recvmsg(csocket, &smb_msg, &iov, 1,
-                                               pdu_length - total_read, 0);
-                       if (server->tcpStatus == CifsExiting) {
-                               /* then will exit */
-                               reconnect = 2;
-                               break;
-                       } else if (server->tcpStatus == CifsNeedReconnect) {
-                               cifs_reconnect(server);
-                               csocket = server->ssocket;
-                               /* Reconnect wakes up rspns q */
-                               /* Now we will reread sock */
-                               reconnect = 1;
-                               break;
-                       } else if (length == -ERESTARTSYS ||
-                                  length == -EAGAIN ||
-                                  length == -EINTR) {
-                               msleep(1); /* minimum sleep to prevent looping,
-                                             allowing socket to clear and app
-                                             threads to set tcpStatus
-                                             CifsNeedReconnect if server hung*/
-                               length = 0;
-                               continue;
-                       } else if (length <= 0) {
-                               cERROR(1, "Received no data, expecting %d",
-                                             pdu_length - total_read);
-                               cifs_reconnect(server);
-                               csocket = server->ssocket;
-                               reconnect = 1;
-                               break;
-                       }
-               }
-               if (reconnect == 2)
+               rc = read_from_socket(server, &smb_msg, &iov, pdu_length,
+                                     &total_read, false);
+               if (rc == 2)
                        break;
-               else if (reconnect == 1)
+               else if (rc == 1)
                        continue;
 
                total_read += 4; /* account for rfc1002 hdr */
@@ -705,7 +693,7 @@ multi_t2_fnd:
        msleep(125);
 
        if (server->ssocket) {
-               sock_release(csocket);
+               sock_release(server->ssocket);
                server->ssocket = NULL;
        }
        /* buffer usually freed in free_mid - need to free it here on exit */