![Pavel Shilovsky](/assets/img/avatar_default.png)
Reviewed-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Pavel Shilovsky <pshilovsky@samba.org> Signed-off-by: Steve French <sfrench@us.ibm.com>
244 lines
7 KiB
C
244 lines
7 KiB
C
/*
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* SMB1 (CIFS) version specific operations
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*
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* Copyright (c) 2012, Jeff Layton <jlayton@redhat.com>
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*
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* This library is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License v2 as published
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* by the Free Software Foundation.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
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* the GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "cifsglob.h"
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#include "cifsproto.h"
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#include "cifs_debug.h"
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#include "cifspdu.h"
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/*
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* An NT cancel request header looks just like the original request except:
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*
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* The Command is SMB_COM_NT_CANCEL
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* The WordCount is zeroed out
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* The ByteCount is zeroed out
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*
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* This function mangles an existing request buffer into a
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* SMB_COM_NT_CANCEL request and then sends it.
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*/
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static int
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send_nt_cancel(struct TCP_Server_Info *server, void *buf,
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struct mid_q_entry *mid)
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{
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int rc = 0;
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struct smb_hdr *in_buf = (struct smb_hdr *)buf;
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/* -4 for RFC1001 length and +2 for BCC field */
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in_buf->smb_buf_length = cpu_to_be32(sizeof(struct smb_hdr) - 4 + 2);
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in_buf->Command = SMB_COM_NT_CANCEL;
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in_buf->WordCount = 0;
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put_bcc(0, in_buf);
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mutex_lock(&server->srv_mutex);
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rc = cifs_sign_smb(in_buf, server, &mid->sequence_number);
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if (rc) {
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mutex_unlock(&server->srv_mutex);
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return rc;
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}
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rc = smb_send(server, in_buf, be32_to_cpu(in_buf->smb_buf_length));
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mutex_unlock(&server->srv_mutex);
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cFYI(1, "issued NT_CANCEL for mid %u, rc = %d",
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in_buf->Mid, rc);
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return rc;
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}
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static bool
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cifs_compare_fids(struct cifsFileInfo *ob1, struct cifsFileInfo *ob2)
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{
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return ob1->netfid == ob2->netfid;
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}
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static unsigned int
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cifs_read_data_offset(char *buf)
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{
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READ_RSP *rsp = (READ_RSP *)buf;
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return le16_to_cpu(rsp->DataOffset);
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}
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static unsigned int
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cifs_read_data_length(char *buf)
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{
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READ_RSP *rsp = (READ_RSP *)buf;
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return (le16_to_cpu(rsp->DataLengthHigh) << 16) +
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le16_to_cpu(rsp->DataLength);
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}
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static struct mid_q_entry *
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cifs_find_mid(struct TCP_Server_Info *server, char *buffer)
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{
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struct smb_hdr *buf = (struct smb_hdr *)buffer;
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struct mid_q_entry *mid;
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spin_lock(&GlobalMid_Lock);
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list_for_each_entry(mid, &server->pending_mid_q, qhead) {
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if (mid->mid == buf->Mid &&
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mid->mid_state == MID_REQUEST_SUBMITTED &&
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le16_to_cpu(mid->command) == buf->Command) {
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spin_unlock(&GlobalMid_Lock);
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return mid;
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}
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}
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spin_unlock(&GlobalMid_Lock);
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return NULL;
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}
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static void
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cifs_add_credits(struct TCP_Server_Info *server, const unsigned int add)
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{
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spin_lock(&server->req_lock);
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server->credits += add;
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server->in_flight--;
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spin_unlock(&server->req_lock);
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wake_up(&server->request_q);
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}
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static void
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cifs_set_credits(struct TCP_Server_Info *server, const int val)
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{
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spin_lock(&server->req_lock);
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server->credits = val;
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server->oplocks = val > 1 ? enable_oplocks : false;
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spin_unlock(&server->req_lock);
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}
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static int *
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cifs_get_credits_field(struct TCP_Server_Info *server)
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{
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return &server->credits;
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}
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/*
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* Find a free multiplex id (SMB mid). Otherwise there could be
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* mid collisions which might cause problems, demultiplexing the
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* wrong response to this request. Multiplex ids could collide if
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* one of a series requests takes much longer than the others, or
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* if a very large number of long lived requests (byte range
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* locks or FindNotify requests) are pending. No more than
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* 64K-1 requests can be outstanding at one time. If no
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* mids are available, return zero. A future optimization
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* could make the combination of mids and uid the key we use
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* to demultiplex on (rather than mid alone).
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* In addition to the above check, the cifs demultiplex
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* code already used the command code as a secondary
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* check of the frame and if signing is negotiated the
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* response would be discarded if the mid were the same
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* but the signature was wrong. Since the mid is not put in the
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* pending queue until later (when it is about to be dispatched)
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* we do have to limit the number of outstanding requests
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* to somewhat less than 64K-1 although it is hard to imagine
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* so many threads being in the vfs at one time.
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*/
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static __u64
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cifs_get_next_mid(struct TCP_Server_Info *server)
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{
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__u64 mid = 0;
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__u16 last_mid, cur_mid;
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bool collision;
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spin_lock(&GlobalMid_Lock);
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/* mid is 16 bit only for CIFS/SMB */
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cur_mid = (__u16)((server->CurrentMid) & 0xffff);
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/* we do not want to loop forever */
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last_mid = cur_mid;
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cur_mid++;
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/*
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* This nested loop looks more expensive than it is.
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* In practice the list of pending requests is short,
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* fewer than 50, and the mids are likely to be unique
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* on the first pass through the loop unless some request
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* takes longer than the 64 thousand requests before it
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* (and it would also have to have been a request that
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* did not time out).
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*/
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while (cur_mid != last_mid) {
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struct mid_q_entry *mid_entry;
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unsigned int num_mids;
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collision = false;
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if (cur_mid == 0)
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cur_mid++;
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num_mids = 0;
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list_for_each_entry(mid_entry, &server->pending_mid_q, qhead) {
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++num_mids;
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if (mid_entry->mid == cur_mid &&
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mid_entry->mid_state == MID_REQUEST_SUBMITTED) {
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/* This mid is in use, try a different one */
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collision = true;
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break;
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}
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}
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/*
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* if we have more than 32k mids in the list, then something
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* is very wrong. Possibly a local user is trying to DoS the
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* box by issuing long-running calls and SIGKILL'ing them. If
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* we get to 2^16 mids then we're in big trouble as this
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* function could loop forever.
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*
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* Go ahead and assign out the mid in this situation, but force
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* an eventual reconnect to clean out the pending_mid_q.
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*/
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if (num_mids > 32768)
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server->tcpStatus = CifsNeedReconnect;
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if (!collision) {
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mid = (__u64)cur_mid;
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server->CurrentMid = mid;
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break;
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}
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cur_mid++;
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}
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spin_unlock(&GlobalMid_Lock);
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return mid;
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}
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struct smb_version_operations smb1_operations = {
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.send_cancel = send_nt_cancel,
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.compare_fids = cifs_compare_fids,
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.setup_request = cifs_setup_request,
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.check_receive = cifs_check_receive,
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.add_credits = cifs_add_credits,
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.set_credits = cifs_set_credits,
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.get_credits_field = cifs_get_credits_field,
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.get_next_mid = cifs_get_next_mid,
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.read_data_offset = cifs_read_data_offset,
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.read_data_length = cifs_read_data_length,
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.map_error = map_smb_to_linux_error,
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.find_mid = cifs_find_mid,
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.check_message = checkSMB,
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.dump_detail = cifs_dump_detail,
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.is_oplock_break = is_valid_oplock_break,
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};
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struct smb_version_values smb1_values = {
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.version_string = SMB1_VERSION_STRING,
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.large_lock_type = LOCKING_ANDX_LARGE_FILES,
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.exclusive_lock_type = 0,
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.shared_lock_type = LOCKING_ANDX_SHARED_LOCK,
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.unlock_lock_type = 0,
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.header_size = sizeof(struct smb_hdr),
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.max_header_size = MAX_CIFS_HDR_SIZE,
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.read_rsp_size = sizeof(READ_RSP),
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};
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