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WSL2-Linux-Kernel
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WSL2-Linux-Kernel/fs/cifs/transport.c

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43 KiB
C
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/*
* fs/cifs/transport.c
*
* Copyright (C) International Business Machines Corp., 2002,2008
* Author(s): Steve French (sfrench@us.ibm.com)
* Jeremy Allison (jra@samba.org) 2006.
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
* the GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/fs.h>
#include <linux/list.h>
#include <linux/gfp.h>
#include <linux/wait.h>
#include <linux/net.h>
#include <linux/delay.h>
#include <linux/freezer.h>
#include <linux/tcp.h>
#include <linux/bvec.h>
#include <linux/highmem.h>
#include <linux/uaccess.h>
#include <asm/processor.h>
#include <linux/mempool.h>
#include <linux/sched/signal.h>
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_debug.h"
#include "smb2proto.h"
#include "smbdirect.h"
/* Max number of iovectors we can use off the stack when sending requests. */
#define CIFS_MAX_IOV_SIZE 8
void
cifs_wake_up_task(struct mid_q_entry *mid)
{
wake_up_process(mid->callback_data);
}
struct mid_q_entry *
AllocMidQEntry(const struct smb_hdr *smb_buffer, struct TCP_Server_Info *server)
{
struct mid_q_entry *temp;
if (server == NULL) {
cifs_dbg(VFS, "Null TCP session in AllocMidQEntry\n");
return NULL;
}
temp = mempool_alloc(cifs_mid_poolp, GFP_NOFS);
memset(temp, 0, sizeof(struct mid_q_entry));
kref_init(&temp->refcount);
temp->mid = get_mid(smb_buffer);
temp->pid = current->pid;
temp->command = cpu_to_le16(smb_buffer->Command);
cifs_dbg(FYI, "For smb_command %d\n", smb_buffer->Command);
/* do_gettimeofday(&temp->when_sent);*/ /* easier to use jiffies */
/* when mid allocated can be before when sent */
temp->when_alloc = jiffies;
temp->server = server;
/*
* The default is for the mid to be synchronous, so the
* default callback just wakes up the current task.
*/
get_task_struct(current);
temp->creator = current;
temp->callback = cifs_wake_up_task;
temp->callback_data = current;
atomic_inc(&midCount);
temp->mid_state = MID_REQUEST_ALLOCATED;
return temp;
}
static void _cifs_mid_q_entry_release(struct kref *refcount)
{
struct mid_q_entry *midEntry =
container_of(refcount, struct mid_q_entry, refcount);
#ifdef CONFIG_CIFS_STATS2
__le16 command = midEntry->server->vals->lock_cmd;
__u16 smb_cmd = le16_to_cpu(midEntry->command);
unsigned long now;
unsigned long roundtrip_time;
#endif
struct TCP_Server_Info *server = midEntry->server;
if (midEntry->resp_buf && (midEntry->mid_flags & MID_WAIT_CANCELLED) &&
midEntry->mid_state == MID_RESPONSE_RECEIVED &&
server->ops->handle_cancelled_mid)
server->ops->handle_cancelled_mid(midEntry->resp_buf, server);
midEntry->mid_state = MID_FREE;
atomic_dec(&midCount);
if (midEntry->large_buf)
cifs_buf_release(midEntry->resp_buf);
else
cifs_small_buf_release(midEntry->resp_buf);
#ifdef CONFIG_CIFS_STATS2
now = jiffies;
if (now < midEntry->when_alloc)
cifs_server_dbg(VFS, "Invalid mid allocation time\n");
roundtrip_time = now - midEntry->when_alloc;
if (smb_cmd < NUMBER_OF_SMB2_COMMANDS) {
if (atomic_read(&server->num_cmds[smb_cmd]) == 0) {
server->slowest_cmd[smb_cmd] = roundtrip_time;
server->fastest_cmd[smb_cmd] = roundtrip_time;
} else {
if (server->slowest_cmd[smb_cmd] < roundtrip_time)
server->slowest_cmd[smb_cmd] = roundtrip_time;
else if (server->fastest_cmd[smb_cmd] > roundtrip_time)
server->fastest_cmd[smb_cmd] = roundtrip_time;
}
cifs_stats_inc(&server->num_cmds[smb_cmd]);
server->time_per_cmd[smb_cmd] += roundtrip_time;
}
/*
* commands taking longer than one second (default) can be indications
* that something is wrong, unless it is quite a slow link or a very
* busy server. Note that this calc is unlikely or impossible to wrap
* as long as slow_rsp_threshold is not set way above recommended max
* value (32767 ie 9 hours) and is generally harmless even if wrong
* since only affects debug counters - so leaving the calc as simple
* comparison rather than doing multiple conversions and overflow
* checks
*/
if ((slow_rsp_threshold != 0) &&
time_after(now, midEntry->when_alloc + (slow_rsp_threshold * HZ)) &&
(midEntry->command != command)) {
/*
* smb2slowcmd[NUMBER_OF_SMB2_COMMANDS] counts by command
* NB: le16_to_cpu returns unsigned so can not be negative below
*/
if (smb_cmd < NUMBER_OF_SMB2_COMMANDS)
cifs_stats_inc(&server->smb2slowcmd[smb_cmd]);
trace_smb3_slow_rsp(smb_cmd, midEntry->mid, midEntry->pid,
midEntry->when_sent, midEntry->when_received);
if (cifsFYI & CIFS_TIMER) {
pr_debug("slow rsp: cmd %d mid %llu",
midEntry->command, midEntry->mid);
cifs_info("A: 0x%lx S: 0x%lx R: 0x%lx\n",
now - midEntry->when_alloc,
now - midEntry->when_sent,
now - midEntry->when_received);
}
}
#endif
put_task_struct(midEntry->creator);
mempool_free(midEntry, cifs_mid_poolp);
}
void cifs_mid_q_entry_release(struct mid_q_entry *midEntry)
{
spin_lock(&GlobalMid_Lock);
kref_put(&midEntry->refcount, _cifs_mid_q_entry_release);
spin_unlock(&GlobalMid_Lock);
}
void DeleteMidQEntry(struct mid_q_entry *midEntry)
{
cifs_mid_q_entry_release(midEntry);
}
void
cifs_delete_mid(struct mid_q_entry *mid)
{
spin_lock(&GlobalMid_Lock);
if (!(mid->mid_flags & MID_DELETED)) {
list_del_init(&mid->qhead);
mid->mid_flags |= MID_DELETED;
}
spin_unlock(&GlobalMid_Lock);
DeleteMidQEntry(mid);
}
/*
* smb_send_kvec - send an array of kvecs to the server
* @server: Server to send the data to
* @smb_msg: Message to send
* @sent: amount of data sent on socket is stored here
*
* Our basic "send data to server" function. Should be called with srv_mutex
* held. The caller is responsible for handling the results.
*/
static int
smb_send_kvec(struct TCP_Server_Info *server, struct msghdr *smb_msg,
size_t *sent)
{
int rc = 0;
int retries = 0;
struct socket *ssocket = server->ssocket;
*sent = 0;
smb_msg->msg_name = (struct sockaddr *) &server->dstaddr;
smb_msg->msg_namelen = sizeof(struct sockaddr);
smb_msg->msg_control = NULL;
smb_msg->msg_controllen = 0;
if (server->noblocksnd)
smb_msg->msg_flags = MSG_DONTWAIT + MSG_NOSIGNAL;
else
smb_msg->msg_flags = MSG_NOSIGNAL;
while (msg_data_left(smb_msg)) {
/*
* If blocking send, we try 3 times, since each can block
* for 5 seconds. For nonblocking we have to try more
* but wait increasing amounts of time allowing time for
* socket to clear. The overall time we wait in either
* case to send on the socket is about 15 seconds.
* Similarly we wait for 15 seconds for a response from
* the server in SendReceive[2] for the server to send
* a response back for most types of requests (except
* SMB Write past end of file which can be slow, and
* blocking lock operations). NFS waits slightly longer
* than CIFS, but this can make it take longer for
* nonresponsive servers to be detected and 15 seconds
* is more than enough time for modern networks to
* send a packet. In most cases if we fail to send
* after the retries we will kill the socket and
* reconnect which may clear the network problem.
*/
rc = sock_sendmsg(ssocket, smb_msg);
if (rc == -EAGAIN) {
retries++;
if (retries >= 14 ||
(!server->noblocksnd && (retries > 2))) {
cifs_server_dbg(VFS, "sends on sock %p stuck for 15 seconds\n",
ssocket);
return -EAGAIN;
}
msleep(1 << retries);
continue;
}
if (rc < 0)
return rc;
if (rc == 0) {
/* should never happen, letting socket clear before
retrying is our only obvious option here */
cifs_server_dbg(VFS, "tcp sent no data\n");
msleep(500);
continue;
}
/* send was at least partially successful */
*sent += rc;
retries = 0; /* in case we get ENOSPC on the next send */
}
return 0;
}
unsigned long
smb_rqst_len(struct TCP_Server_Info *server, struct smb_rqst *rqst)
{
unsigned int i;
struct kvec *iov;
int nvec;
unsigned long buflen = 0;
if (server->vals->header_preamble_size == 0 &&
rqst->rq_nvec >= 2 && rqst->rq_iov[0].iov_len == 4) {
iov = &rqst->rq_iov[1];
nvec = rqst->rq_nvec - 1;
} else {
iov = rqst->rq_iov;
nvec = rqst->rq_nvec;
}
/* total up iov array first */
for (i = 0; i < nvec; i++)
buflen += iov[i].iov_len;
/*
* Add in the page array if there is one. The caller needs to make
* sure rq_offset and rq_tailsz are set correctly. If a buffer of
* multiple pages ends at page boundary, rq_tailsz needs to be set to
* PAGE_SIZE.
*/
if (rqst->rq_npages) {
if (rqst->rq_npages == 1)
buflen += rqst->rq_tailsz;
else {
/*
* If there is more than one page, calculate the
* buffer length based on rq_offset and rq_tailsz
*/
buflen += rqst->rq_pagesz * (rqst->rq_npages - 1) -
rqst->rq_offset;
buflen += rqst->rq_tailsz;
}
}
return buflen;
}
static int
__smb_send_rqst(struct TCP_Server_Info *server, int num_rqst,
struct smb_rqst *rqst)
{
int rc = 0;
struct kvec *iov;
int n_vec;
unsigned int send_length = 0;
unsigned int i, j;
sigset_t mask, oldmask;
size_t total_len = 0, sent, size;
struct socket *ssocket = server->ssocket;
struct msghdr smb_msg;
__be32 rfc1002_marker;
if (cifs_rdma_enabled(server)) {
/* return -EAGAIN when connecting or reconnecting */
rc = -EAGAIN;
if (server->smbd_conn)
rc = smbd_send(server, num_rqst, rqst);
goto smbd_done;
}
if (ssocket == NULL)
return -EAGAIN;
if (fatal_signal_pending(current)) {
cifs_dbg(FYI, "signal pending before send request\n");
return -ERESTARTSYS;
}
/* cork the socket */
tcp_sock_set_cork(ssocket->sk, true);
for (j = 0; j < num_rqst; j++)
send_length += smb_rqst_len(server, &rqst[j]);
rfc1002_marker = cpu_to_be32(send_length);
/*
* We should not allow signals to interrupt the network send because
* any partial send will cause session reconnects thus increasing
* latency of system calls and overload a server with unnecessary
* requests.
*/
sigfillset(&mask);
sigprocmask(SIG_BLOCK, &mask, &oldmask);
/* Generate a rfc1002 marker for SMB2+ */
if (server->vals->header_preamble_size == 0) {
struct kvec hiov = {
.iov_base = &rfc1002_marker,
.iov_len = 4
};
iov_iter_kvec(&smb_msg.msg_iter, WRITE, &hiov, 1, 4);
rc = smb_send_kvec(server, &smb_msg, &sent);
if (rc < 0)
goto unmask;
total_len += sent;
send_length += 4;
}
cifs_dbg(FYI, "Sending smb: smb_len=%u\n", send_length);
for (j = 0; j < num_rqst; j++) {
iov = rqst[j].rq_iov;
n_vec = rqst[j].rq_nvec;
size = 0;
for (i = 0; i < n_vec; i++) {
dump_smb(iov[i].iov_base, iov[i].iov_len);
size += iov[i].iov_len;
}
iov_iter_kvec(&smb_msg.msg_iter, WRITE, iov, n_vec, size);
rc = smb_send_kvec(server, &smb_msg, &sent);
if (rc < 0)
goto unmask;
total_len += sent;
/* now walk the page array and send each page in it */
for (i = 0; i < rqst[j].rq_npages; i++) {
struct bio_vec bvec;
bvec.bv_page = rqst[j].rq_pages[i];
rqst_page_get_length(&rqst[j], i, &bvec.bv_len,
&bvec.bv_offset);
iov_iter_bvec(&smb_msg.msg_iter, WRITE,
&bvec, 1, bvec.bv_len);
rc = smb_send_kvec(server, &smb_msg, &sent);
if (rc < 0)
break;
total_len += sent;
}
}
unmask:
sigprocmask(SIG_SETMASK, &oldmask, NULL);
/*
* If signal is pending but we have already sent the whole packet to
* the server we need to return success status to allow a corresponding
* mid entry to be kept in the pending requests queue thus allowing
* to handle responses from the server by the client.
*
* If only part of the packet has been sent there is no need to hide
* interrupt because the session will be reconnected anyway, so there
* won't be any response from the server to handle.
*/
if (signal_pending(current) && (total_len != send_length)) {
cifs_dbg(FYI, "signal is pending after attempt to send\n");
rc = -ERESTARTSYS;
}
/* uncork it */
tcp_sock_set_cork(ssocket->sk, false);
if ((total_len > 0) && (total_len != send_length)) {
cifs_dbg(FYI, "partial send (wanted=%u sent=%zu): terminating session\n",
send_length, total_len);
/*
* If we have only sent part of an SMB then the next SMB could
* be taken as the remainder of this one. We need to kill the
* socket so the server throws away the partial SMB
*/
server->tcpStatus = CifsNeedReconnect;
trace_smb3_partial_send_reconnect(server->CurrentMid,
server->conn_id, server->hostname);
}
smbd_done:
if (rc < 0 && rc != -EINTR)
cifs_server_dbg(VFS, "Error %d sending data on socket to server\n",
rc);
else if (rc > 0)
rc = 0;
return rc;
}
static int
smb_send_rqst(struct TCP_Server_Info *server, int num_rqst,
struct smb_rqst *rqst, int flags)
{
struct kvec iov;
struct smb2_transform_hdr *tr_hdr;
struct smb_rqst cur_rqst[MAX_COMPOUND];
int rc;
if (!(flags & CIFS_TRANSFORM_REQ))
return __smb_send_rqst(server, num_rqst, rqst);
if (num_rqst > MAX_COMPOUND - 1)
return -ENOMEM;
if (!server->ops->init_transform_rq) {
cifs_server_dbg(VFS, "Encryption requested but transform callback is missing\n");
return -EIO;
}
tr_hdr = kmalloc(sizeof(*tr_hdr), GFP_NOFS);
if (!tr_hdr)
return -ENOMEM;
memset(&cur_rqst[0], 0, sizeof(cur_rqst));
memset(&iov, 0, sizeof(iov));
memset(tr_hdr, 0, sizeof(*tr_hdr));
iov.iov_base = tr_hdr;
iov.iov_len = sizeof(*tr_hdr);
cur_rqst[0].rq_iov = &iov;
cur_rqst[0].rq_nvec = 1;
rc = server->ops->init_transform_rq(server, num_rqst + 1,
&cur_rqst[0], rqst);
if (rc)
goto out;
rc = __smb_send_rqst(server, num_rqst + 1, &cur_rqst[0]);
smb3_free_compound_rqst(num_rqst, &cur_rqst[1]);
out:
kfree(tr_hdr);
return rc;
}
int
smb_send(struct TCP_Server_Info *server, struct smb_hdr *smb_buffer,
unsigned int smb_buf_length)
{
struct kvec iov[2];
struct smb_rqst rqst = { .rq_iov = iov,
.rq_nvec = 2 };
iov[0].iov_base = smb_buffer;
iov[0].iov_len = 4;
iov[1].iov_base = (char *)smb_buffer + 4;
iov[1].iov_len = smb_buf_length;
return __smb_send_rqst(server, 1, &rqst);
}
static int
wait_for_free_credits(struct TCP_Server_Info *server, const int num_credits,
const int timeout, const int flags,
unsigned int *instance)
{
long rc;
int *credits;
int optype;
long int t;
int scredits, in_flight;
if (timeout < 0)
t = MAX_JIFFY_OFFSET;
else
t = msecs_to_jiffies(timeout);
optype = flags & CIFS_OP_MASK;
*instance = 0;
credits = server->ops->get_credits_field(server, optype);
/* Since an echo is already inflight, no need to wait to send another */
if (*credits <= 0 && optype == CIFS_ECHO_OP)
return -EAGAIN;
spin_lock(&server->req_lock);
if ((flags & CIFS_TIMEOUT_MASK) == CIFS_NON_BLOCKING) {
/* oplock breaks must not be held up */
server->in_flight++;
if (server->in_flight > server->max_in_flight)
server->max_in_flight = server->in_flight;
*credits -= 1;
*instance = server->reconnect_instance;
scredits = *credits;
in_flight = server->in_flight;
spin_unlock(&server->req_lock);
trace_smb3_add_credits(server->CurrentMid,
server->conn_id, server->hostname, scredits, -1, in_flight);
cifs_dbg(FYI, "%s: remove %u credits total=%d\n",
__func__, 1, scredits);
return 0;
}
while (1) {
if (*credits < num_credits) {
scredits = *credits;
spin_unlock(&server->req_lock);
cifs_num_waiters_inc(server);
rc = wait_event_killable_timeout(server->request_q,
has_credits(server, credits, num_credits), t);
cifs_num_waiters_dec(server);
if (!rc) {
spin_lock(&server->req_lock);
scredits = *credits;
in_flight = server->in_flight;
spin_unlock(&server->req_lock);
trace_smb3_credit_timeout(server->CurrentMid,
server->conn_id, server->hostname, scredits,
num_credits, in_flight);
cifs_server_dbg(VFS, "wait timed out after %d ms\n",
timeout);
return -EBUSY;
}
if (rc == -ERESTARTSYS)
return -ERESTARTSYS;
spin_lock(&server->req_lock);
} else {
if (server->tcpStatus == CifsExiting) {
spin_unlock(&server->req_lock);
return -ENOENT;
}
/*
* For normal commands, reserve the last MAX_COMPOUND
* credits to compound requests.
* Otherwise these compounds could be permanently
* starved for credits by single-credit requests.
*
* To prevent spinning CPU, block this thread until
* there are >MAX_COMPOUND credits available.
* But only do this is we already have a lot of
* credits in flight to avoid triggering this check
* for servers that are slow to hand out credits on
* new sessions.
*/
if (!optype && num_credits == 1 &&
server->in_flight > 2 * MAX_COMPOUND &&
*credits <= MAX_COMPOUND) {
spin_unlock(&server->req_lock);
cifs_num_waiters_inc(server);
rc = wait_event_killable_timeout(
server->request_q,
has_credits(server, credits,
MAX_COMPOUND + 1),
t);
cifs_num_waiters_dec(server);
if (!rc) {
spin_lock(&server->req_lock);
scredits = *credits;
in_flight = server->in_flight;
spin_unlock(&server->req_lock);
trace_smb3_credit_timeout(
server->CurrentMid,
server->conn_id, server->hostname,
scredits, num_credits, in_flight);
cifs_server_dbg(VFS, "wait timed out after %d ms\n",
timeout);
return -EBUSY;
}
if (rc == -ERESTARTSYS)
return -ERESTARTSYS;
spin_lock(&server->req_lock);
continue;
}
/*
* Can not count locking commands against total
* as they are allowed to block on server.
*/
/* update # of requests on the wire to server */
if ((flags & CIFS_TIMEOUT_MASK) != CIFS_BLOCKING_OP) {
*credits -= num_credits;
server->in_flight += num_credits;
if (server->in_flight > server->max_in_flight)
server->max_in_flight = server->in_flight;
*instance = server->reconnect_instance;
}
scredits = *credits;
in_flight = server->in_flight;
spin_unlock(&server->req_lock);
trace_smb3_add_credits(server->CurrentMid,
server->conn_id, server->hostname, scredits,
-(num_credits), in_flight);
cifs_dbg(FYI, "%s: remove %u credits total=%d\n",
__func__, num_credits, scredits);
break;
}
}
return 0;
}
static int
wait_for_free_request(struct TCP_Server_Info *server, const int flags,
unsigned int *instance)
{
return wait_for_free_credits(server, 1, -1, flags,
instance);
}
static int
wait_for_compound_request(struct TCP_Server_Info *server, int num,
const int flags, unsigned int *instance)
{
int *credits;
int scredits, in_flight;
credits = server->ops->get_credits_field(server, flags & CIFS_OP_MASK);
spin_lock(&server->req_lock);
scredits = *credits;
in_flight = server->in_flight;
if (*credits < num) {
/*
* If the server is tight on resources or just gives us less
* credits for other reasons (e.g. requests are coming out of
* order and the server delays granting more credits until it
* processes a missing mid) and we exhausted most available
* credits there may be situations when we try to send
* a compound request but we don't have enough credits. At this
* point the client needs to decide if it should wait for
* additional credits or fail the request. If at least one
* request is in flight there is a high probability that the
* server will return enough credits to satisfy this compound
* request.
*
* Return immediately if no requests in flight since we will be
* stuck on waiting for credits.
*/
if (server->in_flight == 0) {
spin_unlock(&server->req_lock);
trace_smb3_insufficient_credits(server->CurrentMid,
server->conn_id, server->hostname, scredits,
num, in_flight);
cifs_dbg(FYI, "%s: %d requests in flight, needed %d total=%d\n",
__func__, in_flight, num, scredits);
return -EDEADLK;
}
}
spin_unlock(&server->req_lock);
return wait_for_free_credits(server, num, 60000, flags,
instance);
}
int
cifs_wait_mtu_credits(struct TCP_Server_Info *server, unsigned int size,
unsigned int *num, struct cifs_credits *credits)
{
*num = size;
credits->value = 0;
credits->instance = server->reconnect_instance;
return 0;
}
static int allocate_mid(struct cifs_ses *ses, struct smb_hdr *in_buf,
struct mid_q_entry **ppmidQ)
{
if (ses->server->tcpStatus == CifsExiting) {
return -ENOENT;
}
if (ses->server->tcpStatus == CifsNeedReconnect) {
cifs_dbg(FYI, "tcp session dead - return to caller to retry\n");
return -EAGAIN;
}
if (ses->status == CifsNew) {
if ((in_buf->Command != SMB_COM_SESSION_SETUP_ANDX) &&
(in_buf->Command != SMB_COM_NEGOTIATE))
return -EAGAIN;
/* else ok - we are setting up session */
}
if (ses->status == CifsExiting) {
/* check if SMB session is bad because we are setting it up */
if (in_buf->Command != SMB_COM_LOGOFF_ANDX)
return -EAGAIN;
/* else ok - we are shutting down session */
}
*ppmidQ = AllocMidQEntry(in_buf, ses->server);
if (*ppmidQ == NULL)
return -ENOMEM;
spin_lock(&GlobalMid_Lock);
list_add_tail(&(*ppmidQ)->qhead, &ses->server->pending_mid_q);
spin_unlock(&GlobalMid_Lock);
return 0;
}
static int
wait_for_response(struct TCP_Server_Info *server, struct mid_q_entry *midQ)
{
int error;
error = wait_event_freezekillable_unsafe(server->response_q,
midQ->mid_state != MID_REQUEST_SUBMITTED);
if (error < 0)
return -ERESTARTSYS;
return 0;
}
struct mid_q_entry *
cifs_setup_async_request(struct TCP_Server_Info *server, struct smb_rqst *rqst)
{
int rc;
struct smb_hdr *hdr = (struct smb_hdr *)rqst->rq_iov[0].iov_base;
struct mid_q_entry *mid;
if (rqst->rq_iov[0].iov_len != 4 ||
rqst->rq_iov[0].iov_base + 4 != rqst->rq_iov[1].iov_base)
return ERR_PTR(-EIO);
/* enable signing if server requires it */
if (server->sign)
hdr->Flags2 |= SMBFLG2_SECURITY_SIGNATURE;
mid = AllocMidQEntry(hdr, server);
if (mid == NULL)
return ERR_PTR(-ENOMEM);
rc = cifs_sign_rqst(rqst, server, &mid->sequence_number);
if (rc) {
DeleteMidQEntry(mid);
return ERR_PTR(rc);
}
return mid;
}
/*
* Send a SMB request and set the callback function in the mid to handle
* the result. Caller is responsible for dealing with timeouts.
*/
int
cifs_call_async(struct TCP_Server_Info *server, struct smb_rqst *rqst,
mid_receive_t *receive, mid_callback_t *callback,
mid_handle_t *handle, void *cbdata, const int flags,
const struct cifs_credits *exist_credits)
{
int rc;
struct mid_q_entry *mid;
struct cifs_credits credits = { .value = 0, .instance = 0 };
unsigned int instance;
int optype;
optype = flags & CIFS_OP_MASK;
if ((flags & CIFS_HAS_CREDITS) == 0) {
rc = wait_for_free_request(server, flags, &instance);
if (rc)
return rc;
credits.value = 1;
credits.instance = instance;
} else
instance = exist_credits->instance;
mutex_lock(&server->srv_mutex);
/*
* We can't use credits obtained from the previous session to send this
* request. Check if there were reconnects after we obtained credits and
* return -EAGAIN in such cases to let callers handle it.
*/
if (instance != server->reconnect_instance) {
mutex_unlock(&server->srv_mutex);
add_credits_and_wake_if(server, &credits, optype);
return -EAGAIN;
}
mid = server->ops->setup_async_request(server, rqst);
if (IS_ERR(mid)) {
mutex_unlock(&server->srv_mutex);
add_credits_and_wake_if(server, &credits, optype);
return PTR_ERR(mid);
}
mid->receive = receive;
mid->callback = callback;
mid->callback_data = cbdata;
mid->handle = handle;
mid->mid_state = MID_REQUEST_SUBMITTED;
/* put it on the pending_mid_q */
spin_lock(&GlobalMid_Lock);
list_add_tail(&mid->qhead, &server->pending_mid_q);
spin_unlock(&GlobalMid_Lock);
/*
* Need to store the time in mid before calling I/O. For call_async,
* I/O response may come back and free the mid entry on another thread.
*/
cifs_save_when_sent(mid);
cifs_in_send_inc(server);
rc = smb_send_rqst(server, 1, rqst, flags);
cifs_in_send_dec(server);
if (rc < 0) {
revert_current_mid(server, mid->credits);
server->sequence_number -= 2;
cifs_delete_mid(mid);
}
mutex_unlock(&server->srv_mutex);
if (rc == 0)
return 0;
add_credits_and_wake_if(server, &credits, optype);
return rc;
}
/*
*
* Send an SMB Request. No response info (other than return code)
* needs to be parsed.
*
* flags indicate the type of request buffer and how long to wait
* and whether to log NT STATUS code (error) before mapping it to POSIX error
*
*/
int
SendReceiveNoRsp(const unsigned int xid, struct cifs_ses *ses,
char *in_buf, int flags)
{
int rc;
struct kvec iov[1];
struct kvec rsp_iov;
int resp_buf_type;
iov[0].iov_base = in_buf;
iov[0].iov_len = get_rfc1002_length(in_buf) + 4;
flags |= CIFS_NO_RSP_BUF;
rc = SendReceive2(xid, ses, iov, 1, &resp_buf_type, flags, &rsp_iov);
cifs_dbg(NOISY, "SendRcvNoRsp flags %d rc %d\n", flags, rc);
return rc;
}
static int
cifs_sync_mid_result(struct mid_q_entry *mid, struct TCP_Server_Info *server)
{
int rc = 0;
cifs_dbg(FYI, "%s: cmd=%d mid=%llu state=%d\n",
__func__, le16_to_cpu(mid->command), mid->mid, mid->mid_state);
spin_lock(&GlobalMid_Lock);
switch (mid->mid_state) {
case MID_RESPONSE_RECEIVED:
spin_unlock(&GlobalMid_Lock);
return rc;
case MID_RETRY_NEEDED:
rc = -EAGAIN;
break;
case MID_RESPONSE_MALFORMED:
rc = -EIO;
break;
case MID_SHUTDOWN:
rc = -EHOSTDOWN;
break;
default:
if (!(mid->mid_flags & MID_DELETED)) {
list_del_init(&mid->qhead);
mid->mid_flags |= MID_DELETED;
}
cifs_server_dbg(VFS, "%s: invalid mid state mid=%llu state=%d\n",
__func__, mid->mid, mid->mid_state);
rc = -EIO;
}
spin_unlock(&GlobalMid_Lock);
DeleteMidQEntry(mid);
return rc;
}
static inline int
send_cancel(struct TCP_Server_Info *server, struct smb_rqst *rqst,
struct mid_q_entry *mid)
{
return server->ops->send_cancel ?
server->ops->send_cancel(server, rqst, mid) : 0;
}
int
cifs_check_receive(struct mid_q_entry *mid, struct TCP_Server_Info *server,
bool log_error)
{
unsigned int len = get_rfc1002_length(mid->resp_buf) + 4;
dump_smb(mid->resp_buf, min_t(u32, 92, len));
/* convert the length into a more usable form */
if (server->sign) {
struct kvec iov[2];
int rc = 0;
struct smb_rqst rqst = { .rq_iov = iov,
.rq_nvec = 2 };
iov[0].iov_base = mid->resp_buf;
iov[0].iov_len = 4;
iov[1].iov_base = (char *)mid->resp_buf + 4;
iov[1].iov_len = len - 4;
/* FIXME: add code to kill session */
rc = cifs_verify_signature(&rqst, server,
mid->sequence_number);
if (rc)
cifs_server_dbg(VFS, "SMB signature verification returned error = %d\n",
rc);
}
/* BB special case reconnect tid and uid here? */
return map_and_check_smb_error(mid, log_error);
}
struct mid_q_entry *
cifs_setup_request(struct cifs_ses *ses, struct TCP_Server_Info *ignored,
struct smb_rqst *rqst)
{
int rc;
struct smb_hdr *hdr = (struct smb_hdr *)rqst->rq_iov[0].iov_base;
struct mid_q_entry *mid;
if (rqst->rq_iov[0].iov_len != 4 ||
rqst->rq_iov[0].iov_base + 4 != rqst->rq_iov[1].iov_base)
return ERR_PTR(-EIO);
rc = allocate_mid(ses, hdr, &mid);
if (rc)
return ERR_PTR(rc);
rc = cifs_sign_rqst(rqst, ses->server, &mid->sequence_number);
if (rc) {
cifs_delete_mid(mid);
return ERR_PTR(rc);
}
return mid;
}
static void
cifs_compound_callback(struct mid_q_entry *mid)
{
struct TCP_Server_Info *server = mid->server;
struct cifs_credits credits;
credits.value = server->ops->get_credits(mid);
credits.instance = server->reconnect_instance;
add_credits(server, &credits, mid->optype);
}
static void
cifs_compound_last_callback(struct mid_q_entry *mid)
{
cifs_compound_callback(mid);
cifs_wake_up_task(mid);
}
static void
cifs_cancelled_callback(struct mid_q_entry *mid)
{
cifs_compound_callback(mid);
DeleteMidQEntry(mid);
}
/*
* Return a channel (master if none) of @ses that can be used to send
* regular requests.
*
* If we are currently binding a new channel (negprot/sess.setup),
* return the new incomplete channel.
*/
struct TCP_Server_Info *cifs_pick_channel(struct cifs_ses *ses)
{
uint index = 0;
if (!ses)
return NULL;
if (!ses->binding) {
/* round robin */
if (ses->chan_count > 1) {
index = (uint)atomic_inc_return(&ses->chan_seq);
index %= ses->chan_count;
}
return ses->chans[index].server;
} else {
return cifs_ses_server(ses);
}
}
int
compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
struct TCP_Server_Info *server,
const int flags, const int num_rqst, struct smb_rqst *rqst,
int *resp_buf_type, struct kvec *resp_iov)
{
int i, j, optype, rc = 0;
struct mid_q_entry *midQ[MAX_COMPOUND];
bool cancelled_mid[MAX_COMPOUND] = {false};
struct cifs_credits credits[MAX_COMPOUND] = {
{ .value = 0, .instance = 0 }
};
unsigned int instance;
char *buf;
optype = flags & CIFS_OP_MASK;
for (i = 0; i < num_rqst; i++)
resp_buf_type[i] = CIFS_NO_BUFFER; /* no response buf yet */
if (!ses || !ses->server || !server) {
cifs_dbg(VFS, "Null session\n");
return -EIO;
}
if (server->tcpStatus == CifsExiting)
return -ENOENT;
/*
* Wait for all the requests to become available.
* This approach still leaves the possibility to be stuck waiting for
* credits if the server doesn't grant credits to the outstanding
* requests and if the client is completely idle, not generating any
* other requests.
* This can be handled by the eventual session reconnect.
*/
rc = wait_for_compound_request(server, num_rqst, flags,
&instance);
if (rc)
return rc;
for (i = 0; i < num_rqst; i++) {
credits[i].value = 1;
credits[i].instance = instance;
}
/*
* Make sure that we sign in the same order that we send on this socket
* and avoid races inside tcp sendmsg code that could cause corruption
* of smb data.
*/
mutex_lock(&server->srv_mutex);
/*
* All the parts of the compound chain belong obtained credits from the
* same session. We can not use credits obtained from the previous
* session to send this request. Check if there were reconnects after
* we obtained credits and return -EAGAIN in such cases to let callers
* handle it.
*/
if (instance != server->reconnect_instance) {
mutex_unlock(&server->srv_mutex);
for (j = 0; j < num_rqst; j++)
add_credits(server, &credits[j], optype);
return -EAGAIN;
}
for (i = 0; i < num_rqst; i++) {
midQ[i] = server->ops->setup_request(ses, server, &rqst[i]);
if (IS_ERR(midQ[i])) {
revert_current_mid(server, i);
for (j = 0; j < i; j++)
cifs_delete_mid(midQ[j]);
mutex_unlock(&server->srv_mutex);
/* Update # of requests on wire to server */
for (j = 0; j < num_rqst; j++)
add_credits(server, &credits[j], optype);
return PTR_ERR(midQ[i]);
}
midQ[i]->mid_state = MID_REQUEST_SUBMITTED;
midQ[i]->optype = optype;
/*
* Invoke callback for every part of the compound chain
* to calculate credits properly. Wake up this thread only when
* the last element is received.
*/
if (i < num_rqst - 1)
midQ[i]->callback = cifs_compound_callback;
else
midQ[i]->callback = cifs_compound_last_callback;
}
cifs_in_send_inc(server);
rc = smb_send_rqst(server, num_rqst, rqst, flags);
cifs_in_send_dec(server);
for (i = 0; i < num_rqst; i++)
cifs_save_when_sent(midQ[i]);
if (rc < 0) {
revert_current_mid(server, num_rqst);
server->sequence_number -= 2;
}
mutex_unlock(&server->srv_mutex);
/*
* If sending failed for some reason or it is an oplock break that we
* will not receive a response to - return credits back
*/
if (rc < 0 || (flags & CIFS_NO_SRV_RSP)) {
for (i = 0; i < num_rqst; i++)
add_credits(server, &credits[i], optype);
goto out;
}
/*
* At this point the request is passed to the network stack - we assume
* that any credits taken from the server structure on the client have
* been spent and we can't return them back. Once we receive responses
* we will collect credits granted by the server in the mid callbacks
* and add those credits to the server structure.
*/
/*
* Compounding is never used during session establish.
*/
if ((ses->status == CifsNew) || (optype & CIFS_NEG_OP) || (optype & CIFS_SESS_OP))
smb311_update_preauth_hash(ses, rqst[0].rq_iov,
rqst[0].rq_nvec);
for (i = 0; i < num_rqst; i++) {
rc = wait_for_response(server, midQ[i]);
if (rc != 0)
break;
}
if (rc != 0) {
for (; i < num_rqst; i++) {
cifs_server_dbg(VFS, "Cancelling wait for mid %llu cmd: %d\n",
midQ[i]->mid, le16_to_cpu(midQ[i]->command));
send_cancel(server, &rqst[i], midQ[i]);
spin_lock(&GlobalMid_Lock);
midQ[i]->mid_flags |= MID_WAIT_CANCELLED;
if (midQ[i]->mid_state == MID_REQUEST_SUBMITTED) {
midQ[i]->callback = cifs_cancelled_callback;
cancelled_mid[i] = true;
credits[i].value = 0;
}
spin_unlock(&GlobalMid_Lock);
}
}
for (i = 0; i < num_rqst; i++) {
if (rc < 0)
goto out;
rc = cifs_sync_mid_result(midQ[i], server);
if (rc != 0) {
/* mark this mid as cancelled to not free it below */
cancelled_mid[i] = true;
goto out;
}
if (!midQ[i]->resp_buf ||
midQ[i]->mid_state != MID_RESPONSE_RECEIVED) {
rc = -EIO;
cifs_dbg(FYI, "Bad MID state?\n");
goto out;
}
buf = (char *)midQ[i]->resp_buf;
resp_iov[i].iov_base = buf;
resp_iov[i].iov_len = midQ[i]->resp_buf_size +
server->vals->header_preamble_size;
if (midQ[i]->large_buf)
resp_buf_type[i] = CIFS_LARGE_BUFFER;
else
resp_buf_type[i] = CIFS_SMALL_BUFFER;
rc = server->ops->check_receive(midQ[i], server,
flags & CIFS_LOG_ERROR);
/* mark it so buf will not be freed by cifs_delete_mid */
if ((flags & CIFS_NO_RSP_BUF) == 0)
midQ[i]->resp_buf = NULL;
}
/*
* Compounding is never used during session establish.
*/
if ((ses->status == CifsNew) || (optype & CIFS_NEG_OP) || (optype & CIFS_SESS_OP)) {
struct kvec iov = {
.iov_base = resp_iov[0].iov_base,
.iov_len = resp_iov[0].iov_len
};
smb311_update_preauth_hash(ses, &iov, 1);
}
out:
/*
* This will dequeue all mids. After this it is important that the
* demultiplex_thread will not process any of these mids any futher.
* This is prevented above by using a noop callback that will not
* wake this thread except for the very last PDU.
*/
for (i = 0; i < num_rqst; i++) {
if (!cancelled_mid[i])
cifs_delete_mid(midQ[i]);
}
return rc;
}
int
cifs_send_recv(const unsigned int xid, struct cifs_ses *ses,
struct TCP_Server_Info *server,
struct smb_rqst *rqst, int *resp_buf_type, const int flags,
struct kvec *resp_iov)
{
return compound_send_recv(xid, ses, server, flags, 1,
rqst, resp_buf_type, resp_iov);
}
int
SendReceive2(const unsigned int xid, struct cifs_ses *ses,
struct kvec *iov, int n_vec, int *resp_buf_type /* ret */,
const int flags, struct kvec *resp_iov)
{
struct smb_rqst rqst;
struct kvec s_iov[CIFS_MAX_IOV_SIZE], *new_iov;
int rc;
if (n_vec + 1 > CIFS_MAX_IOV_SIZE) {
new_iov = kmalloc_array(n_vec + 1, sizeof(struct kvec),
GFP_KERNEL);
if (!new_iov) {
/* otherwise cifs_send_recv below sets resp_buf_type */
*resp_buf_type = CIFS_NO_BUFFER;
return -ENOMEM;
}
} else
new_iov = s_iov;
/* 1st iov is a RFC1001 length followed by the rest of the packet */
memcpy(new_iov + 1, iov, (sizeof(struct kvec) * n_vec));
new_iov[0].iov_base = new_iov[1].iov_base;
new_iov[0].iov_len = 4;
new_iov[1].iov_base += 4;
new_iov[1].iov_len -= 4;
memset(&rqst, 0, sizeof(struct smb_rqst));
rqst.rq_iov = new_iov;
rqst.rq_nvec = n_vec + 1;
rc = cifs_send_recv(xid, ses, ses->server,
&rqst, resp_buf_type, flags, resp_iov);
if (n_vec + 1 > CIFS_MAX_IOV_SIZE)
kfree(new_iov);
return rc;
}
int
SendReceive(const unsigned int xid, struct cifs_ses *ses,
struct smb_hdr *in_buf, struct smb_hdr *out_buf,
int *pbytes_returned, const int flags)
{
int rc = 0;
struct mid_q_entry *midQ;
unsigned int len = be32_to_cpu(in_buf->smb_buf_length);
struct kvec iov = { .iov_base = in_buf, .iov_len = len };
struct smb_rqst rqst = { .rq_iov = &iov, .rq_nvec = 1 };
struct cifs_credits credits = { .value = 1, .instance = 0 };
struct TCP_Server_Info *server;
if (ses == NULL) {
cifs_dbg(VFS, "Null smb session\n");
return -EIO;
}
server = ses->server;
if (server == NULL) {
cifs_dbg(VFS, "Null tcp session\n");
return -EIO;
}
if (server->tcpStatus == CifsExiting)
return -ENOENT;
/* Ensure that we do not send more than 50 overlapping requests
to the same server. We may make this configurable later or
use ses->maxReq */
if (len > CIFSMaxBufSize + MAX_CIFS_HDR_SIZE - 4) {
cifs_server_dbg(VFS, "Invalid length, greater than maximum frame, %d\n",
len);
return -EIO;
}
rc = wait_for_free_request(server, flags, &credits.instance);
if (rc)
return rc;
/* make sure that we sign in the same order that we send on this socket
and avoid races inside tcp sendmsg code that could cause corruption
of smb data */
mutex_lock(&server->srv_mutex);
rc = allocate_mid(ses, in_buf, &midQ);
if (rc) {
mutex_unlock(&server->srv_mutex);
/* Update # of requests on wire to server */
add_credits(server, &credits, 0);
return rc;
}
rc = cifs_sign_smb(in_buf, server, &midQ->sequence_number);
if (rc) {
mutex_unlock(&server->srv_mutex);
goto out;
}
midQ->mid_state = MID_REQUEST_SUBMITTED;
cifs_in_send_inc(server);
rc = smb_send(server, in_buf, len);
cifs_in_send_dec(server);
cifs_save_when_sent(midQ);
if (rc < 0)
server->sequence_number -= 2;
mutex_unlock(&server->srv_mutex);
if (rc < 0)
goto out;
rc = wait_for_response(server, midQ);
if (rc != 0) {
send_cancel(server, &rqst, midQ);
spin_lock(&GlobalMid_Lock);
if (midQ->mid_state == MID_REQUEST_SUBMITTED) {
/* no longer considered to be "in-flight" */
midQ->callback = DeleteMidQEntry;
spin_unlock(&GlobalMid_Lock);
add_credits(server, &credits, 0);
return rc;
}
spin_unlock(&GlobalMid_Lock);
}
rc = cifs_sync_mid_result(midQ, server);
if (rc != 0) {
add_credits(server, &credits, 0);
return rc;
}
if (!midQ->resp_buf || !out_buf ||
midQ->mid_state != MID_RESPONSE_RECEIVED) {
rc = -EIO;
cifs_server_dbg(VFS, "Bad MID state?\n");
goto out;
}
*pbytes_returned = get_rfc1002_length(midQ->resp_buf);
memcpy(out_buf, midQ->resp_buf, *pbytes_returned + 4);
rc = cifs_check_receive(midQ, server, 0);
out:
cifs_delete_mid(midQ);
add_credits(server, &credits, 0);
return rc;
}
/* We send a LOCKINGX_CANCEL_LOCK to cause the Windows
blocking lock to return. */
static int
send_lock_cancel(const unsigned int xid, struct cifs_tcon *tcon,
struct smb_hdr *in_buf,
struct smb_hdr *out_buf)
{
int bytes_returned;
struct cifs_ses *ses = tcon->ses;
LOCK_REQ *pSMB = (LOCK_REQ *)in_buf;
/* We just modify the current in_buf to change
the type of lock from LOCKING_ANDX_SHARED_LOCK
or LOCKING_ANDX_EXCLUSIVE_LOCK to
LOCKING_ANDX_CANCEL_LOCK. */
pSMB->LockType = LOCKING_ANDX_CANCEL_LOCK|LOCKING_ANDX_LARGE_FILES;
pSMB->Timeout = 0;
pSMB->hdr.Mid = get_next_mid(ses->server);
return SendReceive(xid, ses, in_buf, out_buf,
&bytes_returned, 0);
}
int
SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
struct smb_hdr *in_buf, struct smb_hdr *out_buf,
int *pbytes_returned)
{
int rc = 0;
int rstart = 0;
struct mid_q_entry *midQ;
struct cifs_ses *ses;
unsigned int len = be32_to_cpu(in_buf->smb_buf_length);
struct kvec iov = { .iov_base = in_buf, .iov_len = len };
struct smb_rqst rqst = { .rq_iov = &iov, .rq_nvec = 1 };
unsigned int instance;
struct TCP_Server_Info *server;
if (tcon == NULL || tcon->ses == NULL) {
cifs_dbg(VFS, "Null smb session\n");
return -EIO;
}
ses = tcon->ses;
server = ses->server;
if (server == NULL) {
cifs_dbg(VFS, "Null tcp session\n");
return -EIO;
}
if (server->tcpStatus == CifsExiting)
return -ENOENT;
/* Ensure that we do not send more than 50 overlapping requests
to the same server. We may make this configurable later or
use ses->maxReq */
if (len > CIFSMaxBufSize + MAX_CIFS_HDR_SIZE - 4) {
cifs_tcon_dbg(VFS, "Invalid length, greater than maximum frame, %d\n",
len);
return -EIO;
}
rc = wait_for_free_request(server, CIFS_BLOCKING_OP, &instance);
if (rc)
return rc;
/* make sure that we sign in the same order that we send on this socket
and avoid races inside tcp sendmsg code that could cause corruption
of smb data */
mutex_lock(&server->srv_mutex);
rc = allocate_mid(ses, in_buf, &midQ);
if (rc) {
mutex_unlock(&server->srv_mutex);
return rc;
}
rc = cifs_sign_smb(in_buf, server, &midQ->sequence_number);
if (rc) {
cifs_delete_mid(midQ);
mutex_unlock(&server->srv_mutex);
return rc;
}
midQ->mid_state = MID_REQUEST_SUBMITTED;
cifs_in_send_inc(server);
rc = smb_send(server, in_buf, len);
cifs_in_send_dec(server);
cifs_save_when_sent(midQ);
if (rc < 0)
server->sequence_number -= 2;
mutex_unlock(&server->srv_mutex);
if (rc < 0) {
cifs_delete_mid(midQ);
return rc;
}
/* Wait for a reply - allow signals to interrupt. */
rc = wait_event_interruptible(server->response_q,
(!(midQ->mid_state == MID_REQUEST_SUBMITTED)) ||
((server->tcpStatus != CifsGood) &&
(server->tcpStatus != CifsNew)));
/* Were we interrupted by a signal ? */
if ((rc == -ERESTARTSYS) &&
(midQ->mid_state == MID_REQUEST_SUBMITTED) &&
((server->tcpStatus == CifsGood) ||
(server->tcpStatus == CifsNew))) {
if (in_buf->Command == SMB_COM_TRANSACTION2) {
/* POSIX lock. We send a NT_CANCEL SMB to cause the
blocking lock to return. */
rc = send_cancel(server, &rqst, midQ);
if (rc) {
cifs_delete_mid(midQ);
return rc;
}
} else {
/* Windows lock. We send a LOCKINGX_CANCEL_LOCK
to cause the blocking lock to return. */
rc = send_lock_cancel(xid, tcon, in_buf, out_buf);
/* If we get -ENOLCK back the lock may have
already been removed. Don't exit in this case. */
if (rc && rc != -ENOLCK) {
cifs_delete_mid(midQ);
return rc;
}
}
rc = wait_for_response(server, midQ);
if (rc) {
send_cancel(server, &rqst, midQ);
spin_lock(&GlobalMid_Lock);
if (midQ->mid_state == MID_REQUEST_SUBMITTED) {
/* no longer considered to be "in-flight" */
midQ->callback = DeleteMidQEntry;
spin_unlock(&GlobalMid_Lock);
return rc;
}
spin_unlock(&GlobalMid_Lock);
}
/* We got the response - restart system call. */
rstart = 1;
}
rc = cifs_sync_mid_result(midQ, server);
if (rc != 0)
return rc;
/* rcvd frame is ok */
if (out_buf == NULL || midQ->mid_state != MID_RESPONSE_RECEIVED) {
rc = -EIO;
cifs_tcon_dbg(VFS, "Bad MID state?\n");
goto out;
}
*pbytes_returned = get_rfc1002_length(midQ->resp_buf);
memcpy(out_buf, midQ->resp_buf, *pbytes_returned + 4);
rc = cifs_check_receive(midQ, server, 0);
out:
cifs_delete_mid(midQ);
if (rstart && rc == -EACCES)
return -ERESTARTSYS;
return rc;
}
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