/*
   *   fs/cifs/smb2misc.c
   *
   *   Copyright (C) International Business Machines  Corp., 2002,2011
   *                 Etersoft, 2012
   *   Author(s): Steve French (sfrench@us.ibm.com)
   *              Pavel Shilovsky (pshilovsky@samba.org) 2012
   *
   *   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/ctype.h>
  #include "smb2pdu.h"
  #include "cifsglob.h"
  #include "cifsproto.h"
  #include "smb2proto.h"
  #include "cifs_debug.h"
  #include "cifs_unicode.h"
  #include "smb2status.h"
  
  static int
  check_smb2_hdr(struct smb2_hdr *hdr, __u64 mid)
  {

  	__u64 wire_mid = le64_to_cpu(hdr->MessageId);

  	/*
  	 * Make sure that this really is an SMB, that it is a response,
  	 * and that the message ids match.
  	 */

  	if ((hdr->ProtocolId == SMB2_PROTO_NUMBER) &&

  	    (mid == wire_mid)) {

  		if (hdr->Flags & SMB2_FLAGS_SERVER_TO_REDIR)
  			return 0;
  		else {
  			/* only one valid case where server sends us request */
  			if (hdr->Command == SMB2_OPLOCK_BREAK)
  				return 0;
  			else

  				cifs_dbg(VFS, "Received Request not response
  ");

  		}
  	} else { /* bad signature or mid */

  		if (hdr->ProtocolId != SMB2_PROTO_NUMBER)

  			cifs_dbg(VFS, "Bad protocol string signature header %x
  ",

  				 le32_to_cpu(hdr->ProtocolId));

  		if (mid != wire_mid)

  			cifs_dbg(VFS, "Mids do not match: %llu and %llu
  ",

  				 mid, wire_mid);

  	}

  	cifs_dbg(VFS, "Bad SMB detected. The Mid=%llu
  ", wire_mid);

  	return 1;
  }
  
  /*
   *  The following table defines the expected "StructureSize" of SMB2 responses
   *  in order by SMB2 command.  This is similar to "wct" in SMB/CIFS responses.
   *
   *  Note that commands are defined in smb2pdu.h in le16 but the array below is
   *  indexed by command in host byte order
   */
  static const __le16 smb2_rsp_struct_sizes[NUMBER_OF_SMB2_COMMANDS] = {

  	/* SMB2_NEGOTIATE */ cpu_to_le16(65),
  	/* SMB2_SESSION_SETUP */ cpu_to_le16(9),
  	/* SMB2_LOGOFF */ cpu_to_le16(4),
  	/* SMB2_TREE_CONNECT */ cpu_to_le16(16),
  	/* SMB2_TREE_DISCONNECT */ cpu_to_le16(4),
  	/* SMB2_CREATE */ cpu_to_le16(89),
  	/* SMB2_CLOSE */ cpu_to_le16(60),
  	/* SMB2_FLUSH */ cpu_to_le16(4),
  	/* SMB2_READ */ cpu_to_le16(17),
  	/* SMB2_WRITE */ cpu_to_le16(17),
  	/* SMB2_LOCK */ cpu_to_le16(4),
  	/* SMB2_IOCTL */ cpu_to_le16(49),

  	/* BB CHECK this ... not listed in documentation */

  	/* SMB2_CANCEL */ cpu_to_le16(0),
  	/* SMB2_ECHO */ cpu_to_le16(4),
  	/* SMB2_QUERY_DIRECTORY */ cpu_to_le16(9),
  	/* SMB2_CHANGE_NOTIFY */ cpu_to_le16(9),
  	/* SMB2_QUERY_INFO */ cpu_to_le16(9),
  	/* SMB2_SET_INFO */ cpu_to_le16(2),

  	/* BB FIXME can also be 44 for lease break */

  	/* SMB2_OPLOCK_BREAK */ cpu_to_le16(24)

  };
  
  int

  smb2_check_message(char *buf, unsigned int length, struct TCP_Server_Info *srvr)

  {
  	struct smb2_hdr *hdr = (struct smb2_hdr *)buf;
  	struct smb2_pdu *pdu = (struct smb2_pdu *)hdr;

  	__u64 mid;

  	__u32 len = get_rfc1002_length(buf);
  	__u32 clc_len;  /* calculated length */
  	int command;
  
  	/* BB disable following printk later */

  	cifs_dbg(FYI, "%s length: 0x%x, smb_buf_length: 0x%x
  ",
  		 __func__, length, len);

  
  	/*
  	 * Add function to do table lookup of StructureSize by command
  	 * ie Validate the wct via smb2_struct_sizes table above
  	 */

  	if (hdr->ProtocolId == SMB2_TRANSFORM_PROTO_NUM) {
  		struct smb2_transform_hdr *thdr =
  			(struct smb2_transform_hdr *)buf;
  		struct cifs_ses *ses = NULL;
  		struct list_head *tmp;
  
  		/* decrypt frame now that it is completely read in */
  		spin_lock(&cifs_tcp_ses_lock);
  		list_for_each(tmp, &srvr->smb_ses_list) {
  			ses = list_entry(tmp, struct cifs_ses, smb_ses_list);
  			if (ses->Suid == thdr->SessionId)
  				break;
  
  			ses = NULL;
  		}
  		spin_unlock(&cifs_tcp_ses_lock);
  		if (ses == NULL) {
  			cifs_dbg(VFS, "no decryption - session id not found
  ");
  			return 1;
  		}
  	}
  
  
  	mid = le64_to_cpu(hdr->MessageId);

  	if (length < sizeof(struct smb2_pdu)) {

  		if ((length >= sizeof(struct smb2_hdr)) && (hdr->Status != 0)) {
  			pdu->StructureSize2 = 0;
  			/*
  			 * As with SMB/CIFS, on some error cases servers may
  			 * not return wct properly
  			 */
  			return 0;
  		} else {

  			cifs_dbg(VFS, "Length less than SMB header size
  ");

  		}
  		return 1;
  	}
  	if (len > CIFSMaxBufSize + MAX_SMB2_HDR_SIZE - 4) {

  		cifs_dbg(VFS, "SMB length greater than maximum, mid=%llu
  ",
  			 mid);

  		return 1;
  	}
  
  	if (check_smb2_hdr(hdr, mid))
  		return 1;

  	if (hdr->StructureSize != SMB2_HEADER_STRUCTURE_SIZE) {

  		cifs_dbg(VFS, "Illegal structure size %u
  ",
  			 le16_to_cpu(hdr->StructureSize));

  		return 1;
  	}
  
  	command = le16_to_cpu(hdr->Command);
  	if (command >= NUMBER_OF_SMB2_COMMANDS) {

  		cifs_dbg(VFS, "Illegal SMB2 command %d
  ", command);

  		return 1;
  	}
  
  	if (smb2_rsp_struct_sizes[command] != pdu->StructureSize2) {

  		if (command != SMB2_OPLOCK_BREAK_HE && (hdr->Status == 0 ||
  		    pdu->StructureSize2 != SMB2_ERROR_STRUCTURE_SIZE2)) {

  			/* error packets have 9 byte structure size */

  			cifs_dbg(VFS, "Illegal response size %u for command %d
  ",
  				 le16_to_cpu(pdu->StructureSize2), command);

  			return 1;

  		} else if (command == SMB2_OPLOCK_BREAK_HE && (hdr->Status == 0)
  			   && (le16_to_cpu(pdu->StructureSize2) != 44)
  			   && (le16_to_cpu(pdu->StructureSize2) != 36)) {
  			/* special case for SMB2.1 lease break message */

  			cifs_dbg(VFS, "Illegal response size %d for oplock break
  ",
  				 le16_to_cpu(pdu->StructureSize2));

  			return 1;

  		}
  	}
  
  	if (4 + len != length) {

  		cifs_dbg(VFS, "Total length %u RFC1002 length %u mismatch mid %llu
  ",
  			 length, 4 + len, mid);

  		return 1;
  	}
  
  	clc_len = smb2_calc_size(hdr);
  
  	if (4 + len != clc_len) {

  		cifs_dbg(FYI, "Calculated size %u length %u mismatch mid %llu
  ",
  			 clc_len, 4 + len, mid);

  		/* create failed on symlink */
  		if (command == SMB2_CREATE_HE &&
  		    hdr->Status == STATUS_STOPPED_ON_SYMLINK)
  			return 0;

  		/* Windows 7 server returns 24 bytes more */
  		if (clc_len + 20 == len && command == SMB2_OPLOCK_BREAK_HE)
  			return 0;

  		/* server can return one byte more due to implied bcc[0] */

  		if (clc_len == 4 + len + 1)
  			return 0;

  
  		/*
  		 * MacOS server pads after SMB2.1 write response with 3 bytes
  		 * of junk. Other servers match RFC1001 len to actual
  		 * SMB2/SMB3 frame length (header + smb2 response specific data)
  		 * Log the server error (once), but allow it and continue
  		 * since the frame is parseable.
  		 */
  		if (clc_len < 4 /* RFC1001 header size */ + len) {
  			printk_once(KERN_WARNING
  				"SMB2 server sent bad RFC1001 len %d not %d
  ",
  				len, clc_len - 4);
  			return 0;
  		}

  		return 1;
  	}
  	return 0;
  }
  
  /*
   * The size of the variable area depends on the offset and length fields
   * located in different fields for various SMB2 responses. SMB2 responses
   * with no variable length info, show an offset of zero for the offset field.
   */
  static const bool has_smb2_data_area[NUMBER_OF_SMB2_COMMANDS] = {
  	/* SMB2_NEGOTIATE */ true,
  	/* SMB2_SESSION_SETUP */ true,
  	/* SMB2_LOGOFF */ false,
  	/* SMB2_TREE_CONNECT */	false,
  	/* SMB2_TREE_DISCONNECT */ false,
  	/* SMB2_CREATE */ true,
  	/* SMB2_CLOSE */ false,
  	/* SMB2_FLUSH */ false,
  	/* SMB2_READ */	true,
  	/* SMB2_WRITE */ false,
  	/* SMB2_LOCK */	false,
  	/* SMB2_IOCTL */ true,
  	/* SMB2_CANCEL */ false, /* BB CHECK this not listed in documentation */
  	/* SMB2_ECHO */ false,
  	/* SMB2_QUERY_DIRECTORY */ true,
  	/* SMB2_CHANGE_NOTIFY */ true,
  	/* SMB2_QUERY_INFO */ true,
  	/* SMB2_SET_INFO */ false,
  	/* SMB2_OPLOCK_BREAK */ false
  };
  
  /*
   * Returns the pointer to the beginning of the data area. Length of the data
   * area and the offset to it (from the beginning of the smb are also returned.
   */

  char *

  smb2_get_data_area_len(int *off, int *len, struct smb2_hdr *hdr)
  {
  	*off = 0;
  	*len = 0;
  
  	/* error responses do not have data area */
  	if (hdr->Status && hdr->Status != STATUS_MORE_PROCESSING_REQUIRED &&
  	    (((struct smb2_err_rsp *)hdr)->StructureSize) ==
  						SMB2_ERROR_STRUCTURE_SIZE2)
  		return NULL;
  
  	/*
  	 * Following commands have data areas so we have to get the location
  	 * of the data buffer offset and data buffer length for the particular
  	 * command.
  	 */
  	switch (hdr->Command) {
  	case SMB2_NEGOTIATE:

  		*off = le16_to_cpu(
  		    ((struct smb2_negotiate_rsp *)hdr)->SecurityBufferOffset);
  		*len = le16_to_cpu(
  		    ((struct smb2_negotiate_rsp *)hdr)->SecurityBufferLength);
  		break;

  	case SMB2_SESSION_SETUP:

  		*off = le16_to_cpu(
  		    ((struct smb2_sess_setup_rsp *)hdr)->SecurityBufferOffset);
  		*len = le16_to_cpu(
  		    ((struct smb2_sess_setup_rsp *)hdr)->SecurityBufferLength);
  		break;

  	case SMB2_CREATE:

  		*off = le32_to_cpu(
  		    ((struct smb2_create_rsp *)hdr)->CreateContextsOffset);
  		*len = le32_to_cpu(
  		    ((struct smb2_create_rsp *)hdr)->CreateContextsLength);
  		break;

  	case SMB2_QUERY_INFO:

  		*off = le16_to_cpu(
  		    ((struct smb2_query_info_rsp *)hdr)->OutputBufferOffset);
  		*len = le32_to_cpu(
  		    ((struct smb2_query_info_rsp *)hdr)->OutputBufferLength);
  		break;
  	case SMB2_READ:

  		*off = ((struct smb2_read_rsp *)hdr)->DataOffset;
  		*len = le32_to_cpu(((struct smb2_read_rsp *)hdr)->DataLength);
  		break;

  	case SMB2_QUERY_DIRECTORY:

  		*off = le16_to_cpu(
  		  ((struct smb2_query_directory_rsp *)hdr)->OutputBufferOffset);
  		*len = le32_to_cpu(
  		  ((struct smb2_query_directory_rsp *)hdr)->OutputBufferLength);
  		break;

  	case SMB2_IOCTL:

  		*off = le32_to_cpu(
  		  ((struct smb2_ioctl_rsp *)hdr)->OutputOffset);
  		*len = le32_to_cpu(((struct smb2_ioctl_rsp *)hdr)->OutputCount);
  		break;

  	case SMB2_CHANGE_NOTIFY:
  	default:
  		/* BB FIXME for unimplemented cases above */

  		cifs_dbg(VFS, "no length check for command
  ");

  		break;
  	}
  
  	/*
  	 * Invalid length or offset probably means data area is invalid, but
  	 * we have little choice but to ignore the data area in this case.
  	 */
  	if (*off > 4096) {

  		cifs_dbg(VFS, "offset %d too large, data area ignored
  ", *off);

  		*len = 0;
  		*off = 0;
  	} else if (*off < 0) {

  		cifs_dbg(VFS, "negative offset %d to data invalid ignore data area
  ",
  			 *off);

  		*off = 0;
  		*len = 0;
  	} else if (*len < 0) {

  		cifs_dbg(VFS, "negative data length %d invalid, data area ignored
  ",
  			 *len);

  		*len = 0;
  	} else if (*len > 128 * 1024) {

  		cifs_dbg(VFS, "data area larger than 128K: %d
  ", *len);

  		*len = 0;
  	}
  
  	/* return pointer to beginning of data area, ie offset from SMB start */
  	if ((*off != 0) && (*len != 0))

  		return (char *)(&hdr->ProtocolId) + *off;

  	else
  		return NULL;
  }
  
  /*
   * Calculate the size of the SMB message based on the fixed header
   * portion, the number of word parameters and the data portion of the message.
   */
  unsigned int

  smb2_calc_size(void *buf)

  {

  	struct smb2_hdr *hdr = (struct smb2_hdr *)buf;

  	struct smb2_pdu *pdu = (struct smb2_pdu *)hdr;
  	int offset; /* the offset from the beginning of SMB to data area */
  	int data_length; /* the length of the variable length data area */
  	/* Structure Size has already been checked to make sure it is 64 */
  	int len = 4 + le16_to_cpu(pdu->hdr.StructureSize);
  
  	/*
  	 * StructureSize2, ie length of fixed parameter area has already
  	 * been checked to make sure it is the correct length.
  	 */
  	len += le16_to_cpu(pdu->StructureSize2);
  
  	if (has_smb2_data_area[le16_to_cpu(hdr->Command)] == false)
  		goto calc_size_exit;
  
  	smb2_get_data_area_len(&offset, &data_length, hdr);

  	cifs_dbg(FYI, "SMB2 data length %d offset %d
  ", data_length, offset);

  
  	if (data_length > 0) {
  		/*
  		 * Check to make sure that data area begins after fixed area,
  		 * Note that last byte of the fixed area is part of data area
  		 * for some commands, typically those with odd StructureSize,
  		 * so we must add one to the calculation (and 4 to account for
  		 * the size of the RFC1001 hdr.
  		 */
  		if (offset + 4 + 1 < len) {

  			cifs_dbg(VFS, "data area offset %d overlaps SMB2 header %d
  ",
  				 offset + 4 + 1, len);

  			data_length = 0;
  		} else {
  			len = 4 + offset + data_length;
  		}
  	}
  calc_size_exit:

  	cifs_dbg(FYI, "SMB2 len %d
  ", len);

  	return len;
  }

  
  /* Note: caller must free return buffer */
  __le16 *
  cifs_convert_path_to_utf16(const char *from, struct cifs_sb_info *cifs_sb)
  {
  	int len;
  	const char *start_of_path;
  	__le16 *to;

  	int map_type;
  
  	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SFM_CHR)
  		map_type = SFM_MAP_UNI_RSVD;
  	else if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR)
  		map_type = SFU_MAP_UNI_RSVD;
  	else
  		map_type = NO_MAP_UNI_RSVD;

  
  	/* Windows doesn't allow paths beginning with \ */
  	if (from[0] == '\\')
  		start_of_path = from + 1;
  	else
  		start_of_path = from;
  	to = cifs_strndup_to_utf16(start_of_path, PATH_MAX, &len,

  				   cifs_sb->local_nls, map_type);

  	return to;
  }

  __le32
  smb2_get_lease_state(struct cifsInodeInfo *cinode)
  {

  	__le32 lease = 0;

  	if (CIFS_CACHE_WRITE(cinode))
  		lease |= SMB2_LEASE_WRITE_CACHING;
  	if (CIFS_CACHE_HANDLE(cinode))
  		lease |= SMB2_LEASE_HANDLE_CACHING;
  	if (CIFS_CACHE_READ(cinode))
  		lease |= SMB2_LEASE_READ_CACHING;
  	return lease;

  }

  struct smb2_lease_break_work {
  	struct work_struct lease_break;
  	struct tcon_link *tlink;
  	__u8 lease_key[16];
  	__le32 lease_state;
  };
  
  static void
  cifs_ses_oplock_break(struct work_struct *work)
  {
  	struct smb2_lease_break_work *lw = container_of(work,
  				struct smb2_lease_break_work, lease_break);
  	int rc;
  
  	rc = SMB2_lease_break(0, tlink_tcon(lw->tlink), lw->lease_key,
  			      lw->lease_state);

  	cifs_dbg(FYI, "Lease release rc %d
  ", rc);

  	cifs_put_tlink(lw->tlink);
  	kfree(lw);
  }

  static bool

  smb2_tcon_has_lease(struct cifs_tcon *tcon, struct smb2_lease_break *rsp,
  		    struct smb2_lease_break_work *lw)
  {
  	bool found;
  	__u8 lease_state;
  	struct list_head *tmp;
  	struct cifsFileInfo *cfile;

  	struct TCP_Server_Info *server = tcon->ses->server;

  	struct cifs_pending_open *open;
  	struct cifsInodeInfo *cinode;
  	int ack_req = le32_to_cpu(rsp->Flags &
  				  SMB2_NOTIFY_BREAK_LEASE_FLAG_ACK_REQUIRED);

  	lease_state = le32_to_cpu(rsp->NewLeaseState);

  
  	list_for_each(tmp, &tcon->openFileList) {
  		cfile = list_entry(tmp, struct cifsFileInfo, tlist);

  		cinode = CIFS_I(d_inode(cfile->dentry));

  
  		if (memcmp(cinode->lease_key, rsp->LeaseKey,
  							SMB2_LEASE_KEY_SIZE))
  			continue;
  
  		cifs_dbg(FYI, "found in the open list
  ");

  		cifs_dbg(FYI, "lease key match, lease break 0x%x
  ",

  			 le32_to_cpu(rsp->NewLeaseState));

  		server->ops->set_oplock_level(cinode, lease_state, 0, NULL);

  
  		if (ack_req)
  			cfile->oplock_break_cancelled = false;
  		else
  			cfile->oplock_break_cancelled = true;
  
  		queue_work(cifsiod_wq, &cfile->oplock_break);
  		kfree(lw);
  		return true;
  	}
  
  	found = false;
  	list_for_each_entry(open, &tcon->pending_opens, olist) {
  		if (memcmp(open->lease_key, rsp->LeaseKey,
  			   SMB2_LEASE_KEY_SIZE))
  			continue;
  
  		if (!found && ack_req) {
  			found = true;
  			memcpy(lw->lease_key, open->lease_key,
  			       SMB2_LEASE_KEY_SIZE);
  			lw->tlink = cifs_get_tlink(open->tlink);
  			queue_work(cifsiod_wq, &lw->lease_break);
  		}
  
  		cifs_dbg(FYI, "found in the pending open list
  ");

  		cifs_dbg(FYI, "lease key match, lease break 0x%x
  ",

  			 le32_to_cpu(rsp->NewLeaseState));
  
  		open->oplock = lease_state;
  	}
  	return found;
  }
  
  static bool
  smb2_is_valid_lease_break(char *buffer)

  {
  	struct smb2_lease_break *rsp = (struct smb2_lease_break *)buffer;
  	struct list_head *tmp, *tmp1, *tmp2;

  	struct TCP_Server_Info *server;

  	struct cifs_ses *ses;
  	struct cifs_tcon *tcon;

  	struct smb2_lease_break_work *lw;

  
  	lw = kmalloc(sizeof(struct smb2_lease_break_work), GFP_KERNEL);

  	if (!lw)

  		return false;

  
  	INIT_WORK(&lw->lease_break, cifs_ses_oplock_break);
  	lw->lease_state = rsp->NewLeaseState;

  	cifs_dbg(FYI, "Checking for lease break
  ");

  
  	/* look up tcon based on tid & uid */
  	spin_lock(&cifs_tcp_ses_lock);

  	list_for_each(tmp, &cifs_tcp_ses_list) {
  		server = list_entry(tmp, struct TCP_Server_Info, tcp_ses_list);

  		list_for_each(tmp1, &server->smb_ses_list) {
  			ses = list_entry(tmp1, struct cifs_ses, smb_ses_list);

  			list_for_each(tmp2, &ses->tcon_list) {
  				tcon = list_entry(tmp2, struct cifs_tcon,
  						  tcon_list);

  				spin_lock(&tcon->open_file_lock);

  				cifs_stats_inc(
  				    &tcon->stats.cifs_stats.num_oplock_brks);
  				if (smb2_tcon_has_lease(tcon, rsp, lw)) {

  					spin_unlock(&tcon->open_file_lock);

  					spin_unlock(&cifs_tcp_ses_lock);
  					return true;

  				}

  				spin_unlock(&tcon->open_file_lock);

  			}

  		}
  	}
  	spin_unlock(&cifs_tcp_ses_lock);

  	kfree(lw);

  	cifs_dbg(FYI, "Can not process lease break - no lease matched
  ");

  	return false;
  }

  bool
  smb2_is_valid_oplock_break(char *buffer, struct TCP_Server_Info *server)
  {
  	struct smb2_oplock_break *rsp = (struct smb2_oplock_break *)buffer;
  	struct list_head *tmp, *tmp1, *tmp2;
  	struct cifs_ses *ses;
  	struct cifs_tcon *tcon;
  	struct cifsInodeInfo *cinode;
  	struct cifsFileInfo *cfile;

  	cifs_dbg(FYI, "Checking for oplock break
  ");

  
  	if (rsp->hdr.Command != SMB2_OPLOCK_BREAK)
  		return false;

  	if (rsp->StructureSize !=

  				smb2_rsp_struct_sizes[SMB2_OPLOCK_BREAK_HE]) {

  		if (le16_to_cpu(rsp->StructureSize) == 44)

  			return smb2_is_valid_lease_break(buffer);

  		else
  			return false;

  	}

  	cifs_dbg(FYI, "oplock level 0x%x
  ", rsp->OplockLevel);

  
  	/* look up tcon based on tid & uid */
  	spin_lock(&cifs_tcp_ses_lock);
  	list_for_each(tmp, &server->smb_ses_list) {
  		ses = list_entry(tmp, struct cifs_ses, smb_ses_list);
  		list_for_each(tmp1, &ses->tcon_list) {
  			tcon = list_entry(tmp1, struct cifs_tcon, tcon_list);
  
  			cifs_stats_inc(&tcon->stats.cifs_stats.num_oplock_brks);

  			spin_lock(&tcon->open_file_lock);

  			list_for_each(tmp2, &tcon->openFileList) {
  				cfile = list_entry(tmp2, struct cifsFileInfo,
  						     tlist);
  				if (rsp->PersistentFid !=
  				    cfile->fid.persistent_fid ||
  				    rsp->VolatileFid !=
  				    cfile->fid.volatile_fid)
  					continue;

  				cifs_dbg(FYI, "file id match, oplock break
  ");

  				cinode = CIFS_I(d_inode(cfile->dentry));

  				spin_lock(&cfile->file_info_lock);

  				if (!CIFS_CACHE_WRITE(cinode) &&

  				    rsp->OplockLevel == SMB2_OPLOCK_LEVEL_NONE)
  					cfile->oplock_break_cancelled = true;
  				else
  					cfile->oplock_break_cancelled = false;

  				set_bit(CIFS_INODE_PENDING_OPLOCK_BREAK,
  					&cinode->flags);
  
  				/*
  				 * Set flag if the server downgrades the oplock
  				 * to L2 else clear.
  				 */
  				if (rsp->OplockLevel)
  					set_bit(
  					   CIFS_INODE_DOWNGRADE_OPLOCK_TO_L2,
  					   &cinode->flags);
  				else
  					clear_bit(
  					   CIFS_INODE_DOWNGRADE_OPLOCK_TO_L2,
  					   &cinode->flags);

  				spin_unlock(&cfile->file_info_lock);

  				queue_work(cifsiod_wq, &cfile->oplock_break);

  				spin_unlock(&tcon->open_file_lock);

  				spin_unlock(&cifs_tcp_ses_lock);
  				return true;
  			}

  			spin_unlock(&tcon->open_file_lock);

  			spin_unlock(&cifs_tcp_ses_lock);

  			cifs_dbg(FYI, "No matching file for oplock break
  ");

  			return true;
  		}
  	}
  	spin_unlock(&cifs_tcp_ses_lock);

  	cifs_dbg(FYI, "Can not process oplock break for non-existent connection
  ");

  	return false;
  }