merge upstream 3.4.0

git-svn-id: svn://svn.debian.org/svn/pkg-samba/trunk/samba@2936 fc4039ab-9d04-0410-8cac-899223bdd6b0

1 files changed, 827 insertions, 0 deletions

diff --git a/source3/smbd/blocking.c b/source3/smbd/blocking.c
new file mode 100644
index 0000000000..42849931f3
--- /dev/null
+++ b/source3/smbd/blocking.c
@@ -0,0 +1,827 @@
+/* 
+   Unix SMB/CIFS implementation.
+   Blocking Locking functions
+   Copyright (C) Jeremy Allison 1998-2003
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "includes.h"
+#include "smbd/globals.h"
+
+#undef DBGC_CLASS
+#define DBGC_CLASS DBGC_LOCKING
+
+/****************************************************************************
+ Determine if this is a secondary element of a chained SMB.
+  **************************************************************************/
+
+static void received_unlock_msg(struct messaging_context *msg,
+				void *private_data,
+				uint32_t msg_type,
+				struct server_id server_id,
+				DATA_BLOB *data);
+
+static void brl_timeout_fn(struct event_context *event_ctx,
+			   struct timed_event *te,
+			   struct timeval now,
+			   void *private_data)
+{
+	SMB_ASSERT(brl_timeout == te);
+	TALLOC_FREE(brl_timeout);
+
+	change_to_root_user();	/* TODO: Possibly run all timed events as
+				 * root */
+
+	process_blocking_lock_queue();
+}
+
+/****************************************************************************
+ After a change to blocking_lock_queue, recalculate the timed_event for the
+ next processing.
+****************************************************************************/
+
+static bool recalc_brl_timeout(void)
+{
+	struct blocking_lock_record *blr;
+	struct timeval next_timeout;
+
+	TALLOC_FREE(brl_timeout);
+
+	next_timeout = timeval_zero();	
+
+	for (blr = blocking_lock_queue; blr; blr = blr->next) {
+		if (timeval_is_zero(&blr->expire_time)) {
+			/*
+			 * If we're blocked on pid 0xFFFFFFFF this is
+			 * a POSIX lock, so calculate a timeout of
+			 * 10 seconds into the future.
+			 */
+                        if (blr->blocking_pid == 0xFFFFFFFF) {
+				struct timeval psx_to = timeval_current_ofs(10, 0);
+				next_timeout = timeval_min(&next_timeout, &psx_to);
+                        }
+
+			continue;
+		}
+
+		if (timeval_is_zero(&next_timeout)) {
+			next_timeout = blr->expire_time;
+		}
+		else {
+			next_timeout = timeval_min(&next_timeout,
+						   &blr->expire_time);
+		}
+	}
+
+	if (timeval_is_zero(&next_timeout)) {
+		DEBUG(10, ("Next timeout = Infinite.\n"));
+		return True;
+	}
+
+	if (DEBUGLVL(10)) {
+		struct timeval cur, from_now;
+
+		cur = timeval_current();
+		from_now = timeval_until(&cur, &next_timeout);
+		DEBUG(10, ("Next timeout = %d.%d seconds from now.\n",
+		    (int)from_now.tv_sec, (int)from_now.tv_usec));
+	}
+
+	if (!(brl_timeout = event_add_timed(smbd_event_context(), NULL,
+					    next_timeout,
+					    brl_timeout_fn, NULL))) {
+		return False;
+	}
+
+	return True;
+}
+
+
+/****************************************************************************
+ Function to push a blocking lock request onto the lock queue.
+****************************************************************************/
+
+bool push_blocking_lock_request( struct byte_range_lock *br_lck,
+		struct smb_request *req,
+		files_struct *fsp,
+		int lock_timeout,
+		int lock_num,
+		uint32_t lock_pid,
+		enum brl_type lock_type,
+		enum brl_flavour lock_flav,
+		uint64_t offset,
+		uint64_t count,
+		uint32_t blocking_pid)
+{
+	struct blocking_lock_record *blr;
+	NTSTATUS status;
+
+	if(req_is_in_chain(req)) {
+		DEBUG(0,("push_blocking_lock_request: cannot queue a chained request (currently).\n"));
+		return False;
+	}
+
+	/*
+	 * Now queue an entry on the blocking lock queue. We setup
+	 * the expiration time here.
+	 */
+
+	blr = talloc(NULL, struct blocking_lock_record);
+	if (blr == NULL) {
+		DEBUG(0,("push_blocking_lock_request: Malloc fail !\n" ));
+		return False;
+	}
+
+	blr->next = NULL;
+	blr->prev = NULL;
+
+	blr->fsp = fsp;
+	if (lock_timeout == -1) {
+		blr->expire_time.tv_sec = 0;
+		blr->expire_time.tv_usec = 0; /* Never expire. */
+	} else {
+		blr->expire_time = timeval_current_ofs(lock_timeout/1000,
+					(lock_timeout % 1000) * 1000);
+	}
+	blr->lock_num = lock_num;
+	blr->lock_pid = lock_pid;
+	blr->blocking_pid = blocking_pid;
+	blr->lock_flav = lock_flav;
+	blr->lock_type = lock_type;
+	blr->offset = offset;
+	blr->count = count;
+      
+	/* Specific brl_lock() implementations can fill this in. */
+	blr->blr_private = NULL;
+
+	/* Add a pending lock record for this. */
+	status = brl_lock(smbd_messaging_context(),
+			br_lck,
+			lock_pid,
+			procid_self(),
+			offset,
+			count,
+			lock_type == READ_LOCK ? PENDING_READ_LOCK : PENDING_WRITE_LOCK,
+			blr->lock_flav,
+			lock_timeout ? True : False, /* blocking_lock. */
+			NULL,
+			blr);
+
+	if (!NT_STATUS_IS_OK(status)) {
+		DEBUG(0,("push_blocking_lock_request: failed to add PENDING_LOCK record.\n"));
+		TALLOC_FREE(blr);
+		return False;
+	}
+
+	SMB_PERFCOUNT_DEFER_OP(&req->pcd, &req->pcd);
+	blr->req = talloc_move(blr, &req);
+
+	DLIST_ADD_END(blocking_lock_queue, blr, struct blocking_lock_record *);
+	recalc_brl_timeout();
+
+	/* Ensure we'll receive messages when this is unlocked. */
+	if (!blocking_lock_unlock_state) {
+		messaging_register(smbd_messaging_context(), NULL,
+				   MSG_SMB_UNLOCK, received_unlock_msg);
+		blocking_lock_unlock_state = true;
+	}
+
+	DEBUG(3,("push_blocking_lock_request: lock request blocked with "
+		"expiry time (%u sec. %u usec) (+%d msec) for fnum = %d, name = %s\n",
+		(unsigned int)blr->expire_time.tv_sec,
+		(unsigned int)blr->expire_time.tv_usec, lock_timeout,
+		blr->fsp->fnum, blr->fsp->fsp_name ));
+
+	/* Push the MID of this packet on the signing queue. */
+	srv_defer_sign_response(blr->req->mid);
+
+	return True;
+}
+
+/****************************************************************************
+ Return a lockingX success SMB.
+*****************************************************************************/
+
+static void reply_lockingX_success(struct blocking_lock_record *blr)
+{
+	reply_outbuf(blr->req, 2, 0);
+
+	/*
+	 * As this message is a lockingX call we must handle
+	 * any following chained message correctly.
+	 * This is normally handled in construct_reply(),
+	 * but as that calls switch_message, we can't use
+	 * that here and must set up the chain info manually.
+	 */
+
+	chain_reply(blr->req);
+	TALLOC_FREE(blr->req->outbuf);
+}
+
+/****************************************************************************
+ Return a generic lock fail error blocking call.
+*****************************************************************************/
+
+static void generic_blocking_lock_error(struct blocking_lock_record *blr, NTSTATUS status)
+{
+	/* whenever a timeout is given w2k maps LOCK_NOT_GRANTED to
+	   FILE_LOCK_CONFLICT! (tridge) */
+	if (NT_STATUS_EQUAL(status, NT_STATUS_LOCK_NOT_GRANTED)) {
+		status = NT_STATUS_FILE_LOCK_CONFLICT;
+	}
+
+	if (NT_STATUS_EQUAL(status, NT_STATUS_FILE_LOCK_CONFLICT)) {
+		/* Store the last lock error. */
+		files_struct *fsp = blr->fsp;
+
+		if (fsp) {
+			fsp->last_lock_failure.context.smbpid = blr->lock_pid;
+			fsp->last_lock_failure.context.tid = fsp->conn->cnum;
+			fsp->last_lock_failure.context.pid = procid_self();
+			fsp->last_lock_failure.start = blr->offset;
+			fsp->last_lock_failure.size = blr->count;
+			fsp->last_lock_failure.fnum = fsp->fnum;
+			fsp->last_lock_failure.lock_type = READ_LOCK; /* Don't care. */
+			fsp->last_lock_failure.lock_flav = blr->lock_flav;
+		}
+	}
+
+	reply_nterror(blr->req, status);
+	if (!srv_send_smb(smbd_server_fd(), (char *)blr->req->outbuf,
+			  blr->req->encrypted, NULL)) {
+		exit_server_cleanly("generic_blocking_lock_error: srv_send_smb failed.");
+	}
+	TALLOC_FREE(blr->req->outbuf);
+}
+
+/****************************************************************************
+ Return a lock fail error for a lockingX call. Undo all the locks we have 
+ obtained first.
+*****************************************************************************/
+
+static void reply_lockingX_error(struct blocking_lock_record *blr, NTSTATUS status)
+{
+	files_struct *fsp = blr->fsp;
+	uint16 num_ulocks = SVAL(blr->req->vwv+6, 0);
+	uint64_t count = (uint64_t)0, offset = (uint64_t) 0;
+	uint32 lock_pid;
+	unsigned char locktype = CVAL(blr->req->vwv+3, 0);
+	bool large_file_format = (locktype & LOCKING_ANDX_LARGE_FILES);
+	uint8_t *data;
+	int i;
+
+	data = (uint8_t *)blr->req->buf
+		+ ((large_file_format ? 20 : 10)*num_ulocks);
+
+	/* 
+	 * Data now points at the beginning of the list
+	 * of smb_lkrng structs.
+	 */
+
+	/*
+	 * Ensure we don't do a remove on the lock that just failed,
+	 * as under POSIX rules, if we have a lock already there, we
+	 * will delete it (and we shouldn't) .....
+	 */
+
+	for(i = blr->lock_num - 1; i >= 0; i--) {
+		bool err;
+
+		lock_pid = get_lock_pid( data, i, large_file_format);
+		count = get_lock_count( data, i, large_file_format);
+		offset = get_lock_offset( data, i, large_file_format, &err);
+
+		/*
+		 * We know err cannot be set as if it was the lock
+		 * request would never have been queued. JRA.
+		 */
+
+		do_unlock(smbd_messaging_context(),
+			fsp,
+			lock_pid,
+			count,
+			offset,
+			WINDOWS_LOCK);
+	}
+
+	generic_blocking_lock_error(blr, status);
+}
+
+/****************************************************************************
+ Return a lock fail error.
+*****************************************************************************/
+
+static void blocking_lock_reply_error(struct blocking_lock_record *blr, NTSTATUS status)
+{
+	DEBUG(10, ("Replying with error=%s. BLR = %p\n", nt_errstr(status), blr));
+
+	switch(blr->req->cmd) {
+	case SMBlockingX:
+		reply_lockingX_error(blr, status);
+		break;
+	case SMBtrans2:
+	case SMBtranss2:
+		reply_nterror(blr->req, status);
+
+		/*
+		 * construct_reply_common has done us the favor to pre-fill
+		 * the command field with SMBtranss2 which is wrong :-)
+		 */
+		SCVAL(blr->req->outbuf,smb_com,SMBtrans2);
+
+		if (!srv_send_smb(smbd_server_fd(),
+				  (char *)blr->req->outbuf,
+				  IS_CONN_ENCRYPTED(blr->fsp->conn),
+				  NULL)) {
+			exit_server_cleanly("blocking_lock_reply_error: "
+					    "srv_send_smb failed.");
+		}
+		TALLOC_FREE(blr->req->outbuf);
+		break;
+	default:
+		DEBUG(0,("blocking_lock_reply_error: PANIC - unknown type on blocking lock queue - exiting.!\n"));
+		exit_server("PANIC - unknown type on blocking lock queue");
+	}
+}
+
+/****************************************************************************
+ Attempt to finish off getting all pending blocking locks for a lockingX call.
+ Returns True if we want to be removed from the list.
+*****************************************************************************/
+
+static bool process_lockingX(struct blocking_lock_record *blr)
+{
+	unsigned char locktype = CVAL(blr->req->vwv+3, 0);
+	files_struct *fsp = blr->fsp;
+	uint16 num_ulocks = SVAL(blr->req->vwv+6, 0);
+	uint16 num_locks = SVAL(blr->req->vwv+7, 0);
+	uint64_t count = (uint64_t)0, offset = (uint64_t)0;
+	uint32 lock_pid;
+	bool large_file_format = (locktype & LOCKING_ANDX_LARGE_FILES);
+	uint8_t *data;
+	NTSTATUS status = NT_STATUS_OK;
+
+	data = (uint8_t *)blr->req->buf
+		+ ((large_file_format ? 20 : 10)*num_ulocks);
+
+	/* 
+	 * Data now points at the beginning of the list
+	 * of smb_lkrng structs.
+	 */
+
+	for(; blr->lock_num < num_locks; blr->lock_num++) {
+		struct byte_range_lock *br_lck = NULL;
+		bool err;
+
+		lock_pid = get_lock_pid( data, blr->lock_num, large_file_format);
+		count = get_lock_count( data, blr->lock_num, large_file_format);
+		offset = get_lock_offset( data, blr->lock_num, large_file_format, &err);
+
+		/*
+		 * We know err cannot be set as if it was the lock
+		 * request would never have been queued. JRA.
+		 */
+		errno = 0;
+		br_lck = do_lock(smbd_messaging_context(),
+				fsp,
+				lock_pid,
+				count,
+				offset, 
+				((locktype & LOCKING_ANDX_SHARED_LOCK) ?
+					READ_LOCK : WRITE_LOCK),
+				WINDOWS_LOCK,
+				True,
+				&status,
+				&blr->blocking_pid,
+				blr);
+
+		TALLOC_FREE(br_lck);
+
+		if (NT_STATUS_IS_ERR(status)) {
+			break;
+		}
+	}
+
+	if(blr->lock_num == num_locks) {
+		/*
+		 * Success - we got all the locks.
+		 */
+
+		DEBUG(3,("process_lockingX file = %s, fnum=%d type=%d num_locks=%d\n",
+			 fsp->fsp_name, fsp->fnum, (unsigned int)locktype, num_locks) );
+
+		reply_lockingX_success(blr);
+		return True;
+	}
+
+	if (!NT_STATUS_EQUAL(status,NT_STATUS_LOCK_NOT_GRANTED) &&
+	    !NT_STATUS_EQUAL(status,NT_STATUS_FILE_LOCK_CONFLICT)) {
+		/*
+		 * We have other than a "can't get lock"
+		 * error. Free any locks we had and return an error.
+		 * Return True so we get dequeued.
+		 */
+		blocking_lock_reply_error(blr, status);
+		return True;
+	}
+
+	/*
+	 * Still can't get all the locks - keep waiting.
+	 */
+
+	DEBUG(10,("process_lockingX: only got %d locks of %d needed for file %s, fnum = %d. \
+Waiting....\n", 
+		  blr->lock_num, num_locks, fsp->fsp_name, fsp->fnum));
+
+	return False;
+}
+
+/****************************************************************************
+ Attempt to get the posix lock request from a SMBtrans2 call.
+ Returns True if we want to be removed from the list.
+*****************************************************************************/
+
+static bool process_trans2(struct blocking_lock_record *blr)
+{
+	char params[2];
+	NTSTATUS status;
+	struct byte_range_lock *br_lck = do_lock(smbd_messaging_context(),
+						blr->fsp,
+						blr->lock_pid,
+						blr->count,
+						blr->offset,
+						blr->lock_type,
+						blr->lock_flav,
+						True,
+						&status,
+						&blr->blocking_pid,
+						blr);
+	TALLOC_FREE(br_lck);
+
+	if (!NT_STATUS_IS_OK(status)) {
+		if (ERROR_WAS_LOCK_DENIED(status)) {
+			/* Still can't get the lock, just keep waiting. */
+			return False;
+		}	
+		/*
+		 * We have other than a "can't get lock"
+		 * error. Send an error and return True so we get dequeued.
+		 */
+		blocking_lock_reply_error(blr, status);
+		return True;
+	}
+
+	/* We finally got the lock, return success. */
+
+	SSVAL(params,0,0);
+	/* Fake up max_data_bytes here - we know it fits. */
+	send_trans2_replies(blr->fsp->conn, blr->req, params, 2, NULL, 0, 0xffff);
+	return True;
+}
+
+
+/****************************************************************************
+ Process a blocking lock SMB.
+ Returns True if we want to be removed from the list.
+*****************************************************************************/
+
+static bool blocking_lock_record_process(struct blocking_lock_record *blr)
+{
+	switch(blr->req->cmd) {
+		case SMBlockingX:
+			return process_lockingX(blr);
+		case SMBtrans2:
+		case SMBtranss2:
+			return process_trans2(blr);
+		default:
+			DEBUG(0,("blocking_lock_record_process: PANIC - unknown type on blocking lock queue - exiting.!\n"));
+			exit_server("PANIC - unknown type on blocking lock queue");
+	}
+	return False; /* Keep compiler happy. */
+}
+
+/****************************************************************************
+ Cancel entries by fnum from the blocking lock pending queue.
+*****************************************************************************/
+
+void cancel_pending_lock_requests_by_fid(files_struct *fsp, struct byte_range_lock *br_lck)
+{
+	struct blocking_lock_record *blr, *blr_cancelled, *next = NULL;
+
+	for(blr = blocking_lock_queue; blr; blr = next) {
+		unsigned char locktype = 0;
+
+		next = blr->next;
+		if (blr->fsp->fnum != fsp->fnum) {
+			continue;
+		}
+
+		if (blr->req->cmd == SMBlockingX) {
+			locktype = CVAL(blr->req->vwv+3, 0);
+		}
+
+		DEBUG(10, ("remove_pending_lock_requests_by_fid - removing "
+			   "request type %d for file %s fnum = %d\n",
+			   blr->req->cmd, fsp->fsp_name, fsp->fnum));
+
+		blr_cancelled = blocking_lock_cancel(fsp,
+				     blr->lock_pid,
+				     blr->offset,
+				     blr->count,
+				     blr->lock_flav,
+				     locktype,
+				     NT_STATUS_RANGE_NOT_LOCKED);
+
+		SMB_ASSERT(blr_cancelled == blr);
+
+		brl_lock_cancel(br_lck,
+				blr->lock_pid,
+				procid_self(),
+				blr->offset,
+				blr->count,
+				blr->lock_flav,
+				blr);
+
+		/* We're closing the file fsp here, so ensure
+		 * we don't have a dangling pointer. */
+		blr->fsp = NULL;
+	}
+}
+
+/****************************************************************************
+ Delete entries by mid from the blocking lock pending queue. Always send reply.
+*****************************************************************************/
+
+void remove_pending_lock_requests_by_mid(int mid)
+{
+	struct blocking_lock_record *blr, *next = NULL;
+
+	for(blr = blocking_lock_queue; blr; blr = next) {
+		files_struct *fsp;
+		struct byte_range_lock *br_lck;
+
+		next = blr->next;
+
+		if (blr->req->mid != mid) {
+			continue;
+		}
+
+		fsp = blr->fsp;
+		br_lck = brl_get_locks(talloc_tos(), fsp);
+
+		if (br_lck) {
+			DEBUG(10, ("remove_pending_lock_requests_by_mid - "
+				   "removing request type %d for file %s fnum "
+				   "= %d\n", blr->req->cmd, fsp->fsp_name,
+				   fsp->fnum ));
+
+			brl_lock_cancel(br_lck,
+					blr->lock_pid,
+					procid_self(),
+					blr->offset,
+					blr->count,
+					blr->lock_flav,
+					blr);
+			TALLOC_FREE(br_lck);
+		}
+
+		blocking_lock_reply_error(blr,NT_STATUS_FILE_LOCK_CONFLICT);
+		DLIST_REMOVE(blocking_lock_queue, blr);
+		TALLOC_FREE(blr);
+	}
+}
+
+/****************************************************************************
+ Is this mid a blocking lock request on the queue ?
+*****************************************************************************/
+
+bool blocking_lock_was_deferred(int mid)
+{
+	struct blocking_lock_record *blr, *next = NULL;
+
+	for(blr = blocking_lock_queue; blr; blr = next) {
+		next = blr->next;
+		if(blr->req->mid == mid) {
+			return True;
+		}
+	}
+	return False;
+}
+
+/****************************************************************************
+  Set a flag as an unlock request affects one of our pending locks.
+*****************************************************************************/
+
+static void received_unlock_msg(struct messaging_context *msg,
+				void *private_data,
+				uint32_t msg_type,
+				struct server_id server_id,
+				DATA_BLOB *data)
+{
+	DEBUG(10,("received_unlock_msg\n"));
+	process_blocking_lock_queue();
+}
+
+/****************************************************************************
+ Process the blocking lock queue. Note that this is only called as root.
+*****************************************************************************/
+
+void process_blocking_lock_queue(void)
+{
+	struct timeval tv_curr = timeval_current();
+	struct blocking_lock_record *blr, *next = NULL;
+	bool recalc_timeout = False;
+
+	/*
+	 * Go through the queue and see if we can get any of the locks.
+	 */
+
+	for (blr = blocking_lock_queue; blr; blr = next) {
+
+		next = blr->next;
+
+		/*
+		 * Go through the remaining locks and try and obtain them.
+		 * The call returns True if all locks were obtained successfully
+		 * and False if we still need to wait.
+		 */
+
+		DEBUG(10, ("Processing BLR = %p\n", blr));
+
+		if(blocking_lock_record_process(blr)) {
+			struct byte_range_lock *br_lck = brl_get_locks(
+				talloc_tos(), blr->fsp);
+
+			DEBUG(10, ("BLR_process returned true: cancelling and "
+			    "removing lock. BLR = %p\n", blr));
+
+			if (br_lck) {
+				brl_lock_cancel(br_lck,
+					blr->lock_pid,
+					procid_self(),
+					blr->offset,
+					blr->count,
+					blr->lock_flav,
+					blr);
+				TALLOC_FREE(br_lck);
+			}
+
+			DLIST_REMOVE(blocking_lock_queue, blr);
+			TALLOC_FREE(blr);
+			recalc_timeout = True;
+			continue;
+		}
+
+		/*
+		 * We couldn't get the locks for this record on the list.
+		 * If the time has expired, return a lock error.
+		 */
+
+		if (!timeval_is_zero(&blr->expire_time) && timeval_compare(&blr->expire_time, &tv_curr) <= 0) {
+			struct byte_range_lock *br_lck = brl_get_locks(
+				talloc_tos(), blr->fsp);
+
+			DEBUG(10, ("Lock timed out! BLR = %p\n", blr));
+
+			/*
+			 * Lock expired - throw away all previously
+			 * obtained locks and return lock error.
+			 */
+
+			if (br_lck) {
+				DEBUG(5,("process_blocking_lock_queue: "
+					 "pending lock fnum = %d for file %s "
+					 "timed out.\n", blr->fsp->fnum,
+					 blr->fsp->fsp_name ));
+
+				brl_lock_cancel(br_lck,
+					blr->lock_pid,
+					procid_self(),
+					blr->offset,
+					blr->count,
+					blr->lock_flav,
+					blr);
+				TALLOC_FREE(br_lck);
+			}
+
+			blocking_lock_reply_error(blr,NT_STATUS_FILE_LOCK_CONFLICT);
+			DLIST_REMOVE(blocking_lock_queue, blr);
+			TALLOC_FREE(blr);
+			recalc_timeout = True;
+		}
+	}
+
+	if (recalc_timeout) {
+		recalc_brl_timeout();
+	}
+}
+
+/****************************************************************************
+ Handle a cancel message. Lock already moved onto the cancel queue.
+*****************************************************************************/
+
+#define MSG_BLOCKING_LOCK_CANCEL_SIZE (sizeof(struct blocking_lock_record *) + sizeof(NTSTATUS))
+
+static void process_blocking_lock_cancel_message(struct messaging_context *ctx,
+						 void *private_data,
+						 uint32_t msg_type,
+						 struct server_id server_id,
+						 DATA_BLOB *data)
+{
+	NTSTATUS err;
+	const char *msg = (const char *)data->data;
+	struct blocking_lock_record *blr;
+
+	if (data->data == NULL) {
+		smb_panic("process_blocking_lock_cancel_message: null msg");
+	}
+
+	if (data->length != MSG_BLOCKING_LOCK_CANCEL_SIZE) {
+		DEBUG(0, ("process_blocking_lock_cancel_message: "
+			  "Got invalid msg len %d\n", (int)data->length));
+		smb_panic("process_blocking_lock_cancel_message: bad msg");
+        }
+
+	memcpy(&blr, msg, sizeof(blr));
+	memcpy(&err, &msg[sizeof(blr)], sizeof(NTSTATUS));
+
+	DEBUG(10,("process_blocking_lock_cancel_message: returning error %s\n",
+		nt_errstr(err) ));
+
+	blocking_lock_reply_error(blr, err);
+	DLIST_REMOVE(blocking_lock_cancelled_queue, blr);
+	TALLOC_FREE(blr);
+}
+
+/****************************************************************************
+ Send ourselves a blocking lock cancelled message. Handled asynchronously above.
+ Returns the blocking_lock_record that is being cancelled.
+*****************************************************************************/
+
+struct blocking_lock_record *blocking_lock_cancel(files_struct *fsp,
+			uint32 lock_pid,
+			uint64_t offset,
+			uint64_t count,
+			enum brl_flavour lock_flav,
+			unsigned char locktype,
+                        NTSTATUS err)
+{
+	char msg[MSG_BLOCKING_LOCK_CANCEL_SIZE];
+	struct blocking_lock_record *blr;
+
+	if (!blocking_lock_cancel_state) {
+		/* Register our message. */
+		messaging_register(smbd_messaging_context(), NULL,
+				   MSG_SMB_BLOCKING_LOCK_CANCEL,
+				   process_blocking_lock_cancel_message);
+
+		blocking_lock_cancel_state = True;
+	}
+
+	for (blr = blocking_lock_queue; blr; blr = blr->next) {
+		if (fsp == blr->fsp &&
+				lock_pid == blr->lock_pid &&
+				offset == blr->offset &&
+				count == blr->count &&
+				lock_flav == blr->lock_flav) {
+			break;
+		}
+	}
+
+	if (!blr) {
+		return NULL;
+	}
+
+	/* Check the flags are right. */
+	if (blr->req->cmd == SMBlockingX &&
+		(locktype & LOCKING_ANDX_LARGE_FILES) !=
+			(CVAL(blr->req->vwv+3, 0) & LOCKING_ANDX_LARGE_FILES)) {
+		return NULL;
+	}
+
+	/* Move to cancelled queue. */
+	DLIST_REMOVE(blocking_lock_queue, blr);
+	DLIST_ADD(blocking_lock_cancelled_queue, blr);
+
+	/* Create the message. */
+	memcpy(msg, &blr, sizeof(blr));
+	memcpy(&msg[sizeof(blr)], &err, sizeof(NTSTATUS));
+
+	messaging_send_buf(smbd_messaging_context(), procid_self(),
+			   MSG_SMB_BLOCKING_LOCK_CANCEL,
+			   (uint8 *)&msg, sizeof(msg));
+
+	return blr;
+}