CIFS: Simplify socket reading in demultiplex thread

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>

1 files changed, 71 insertions, 83 deletions

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 217d36587185..a2e9fcf4a996 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -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 */