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CIFS: Simplify socket reading in demultiplex thread
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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>
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Pavel Shilovsky authored and Steve French committed Aug 1, 2011
1 parent 3d9c247 commit e7015fb
Showing 1 changed file with 71 additions and 83 deletions.
154 changes: 71 additions & 83 deletions fs/cifs/connect.c
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Original file line number Diff line number Diff line change
Expand Up @@ -358,6 +358,64 @@ allocate_buffers(char **bigbuf, char **smallbuf, unsigned int size,
return true;
}

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)
{
Expand All @@ -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));
Expand Down Expand Up @@ -412,51 +469,18 @@ cifs_demultiplex_thread(void *p)
"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 */
Expand Down Expand Up @@ -493,14 +517,12 @@ cifs_demultiplex_thread(void *p)
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;
}

Expand All @@ -510,59 +532,25 @@ cifs_demultiplex_thread(void *p)
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 */
Expand Down Expand Up @@ -705,7 +693,7 @@ cifs_demultiplex_thread(void *p)
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 */
Expand Down

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