Adding upstream version 2:4.17.12+dfsg.upstream/2%4.17.12+dfsgupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1374 insertions, 0 deletions

diff --git a/source3/locking/posix.c b/source3/locking/posix.c
new file mode 100644
index 0000000..536d8bf
--- /dev/null
+++ b/source3/locking/posix.c
@@ -0,0 +1,1374 @@
+/* 
+   Unix SMB/CIFS implementation.
+   Locking functions
+   Copyright (C) Jeremy Allison 1992-2006
+   
+   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/>.
+
+   Revision History:
+
+   POSIX locking support. Jeremy Allison (jeremy@valinux.com), Apr. 2000.
+*/
+
+#include "includes.h"
+#include "system/filesys.h"
+#include "lib/util/server_id.h"
+#include "locking/proto.h"
+#include "dbwrap/dbwrap.h"
+#include "dbwrap/dbwrap_rbt.h"
+#include "util_tdb.h"
+#include "smbd/fd_handle.h"
+
+#undef DBGC_CLASS
+#define DBGC_CLASS DBGC_LOCKING
+
+/*
+ * The pending close database handle.
+ */
+
+static struct db_context *posix_pending_close_db;
+
+/****************************************************************************
+ First - the functions that deal with the underlying system locks - these
+ functions are used no matter if we're mapping CIFS Windows locks or CIFS
+ POSIX locks onto POSIX.
+****************************************************************************/
+
+/****************************************************************************
+ Utility function to map a lock type correctly depending on the open
+ mode of a file.
+****************************************************************************/
+
+static int map_posix_lock_type( files_struct *fsp, enum brl_type lock_type)
+{
+	if ((lock_type == WRITE_LOCK) && !fsp->fsp_flags.can_write) {
+		/*
+		 * Many UNIX's cannot get a write lock on a file opened read-only.
+		 * Win32 locking semantics allow this.
+		 * Do the best we can and attempt a read-only lock.
+		 */
+		DEBUG(10,("map_posix_lock_type: Downgrading write lock to read due to read-only file.\n"));
+		return F_RDLCK;
+	}
+
+	/*
+	 * This return should be the most normal, as we attempt
+	 * to always open files read/write.
+	 */
+
+	return (lock_type == READ_LOCK) ? F_RDLCK : F_WRLCK;
+}
+
+/****************************************************************************
+ Debugging aid :-).
+****************************************************************************/
+
+static const char *posix_lock_type_name(int lock_type)
+{
+	return (lock_type == F_RDLCK) ? "READ" : "WRITE";
+}
+
+/****************************************************************************
+ Check to see if the given unsigned lock range is within the possible POSIX
+ range. Modifies the given args to be in range if possible, just returns
+ False if not.
+****************************************************************************/
+
+#define SMB_OFF_T_BITS (sizeof(off_t)*8)
+
+static bool posix_lock_in_range(off_t *offset_out, off_t *count_out,
+				uint64_t u_offset, uint64_t u_count)
+{
+	off_t offset = (off_t)u_offset;
+	off_t count = (off_t)u_count;
+
+	/*
+	 * For the type of system we are, attempt to
+	 * find the maximum positive lock offset as an off_t.
+	 */
+
+#if defined(MAX_POSITIVE_LOCK_OFFSET) /* Some systems have arbitrary limits. */
+
+	off_t max_positive_lock_offset = (MAX_POSITIVE_LOCK_OFFSET);
+#else
+	/*
+	 * In this case off_t is 64 bits,
+	 * and the underlying system can handle 64 bit signed locks.
+	 */
+
+	off_t mask2 = ((off_t)0x4) << (SMB_OFF_T_BITS-4);
+	off_t mask = (mask2<<1);
+	off_t max_positive_lock_offset = ~mask;
+
+#endif
+	/*
+	 * POSIX locks of length zero mean lock to end-of-file.
+	 * Win32 locks of length zero are point probes. Ignore
+	 * any Win32 locks of length zero. JRA.
+	 */
+
+	if (count == 0) {
+		DEBUG(10,("posix_lock_in_range: count = 0, ignoring.\n"));
+		return False;
+	}
+
+	/*
+	 * If the given offset was > max_positive_lock_offset then we cannot map this at all
+	 * ignore this lock.
+	 */
+
+	if (u_offset & ~((uint64_t)max_positive_lock_offset)) {
+		DEBUG(10, ("posix_lock_in_range: (offset = %ju) offset > %ju "
+			   "and we cannot handle this. Ignoring lock.\n",
+			   (uintmax_t)u_offset,
+			   (uintmax_t)max_positive_lock_offset));
+		return False;
+	}
+
+	/*
+	 * We must truncate the count to less than max_positive_lock_offset.
+	 */
+
+	if (u_count & ~((uint64_t)max_positive_lock_offset)) {
+		count = max_positive_lock_offset;
+	}
+
+	/*
+	 * Truncate count to end at max lock offset.
+	 */
+
+	if (offset > INT64_MAX - count ||
+	    offset + count > max_positive_lock_offset) {
+		count = max_positive_lock_offset - offset;
+	}
+
+	/*
+	 * If we ate all the count, ignore this lock.
+	 */
+
+	if (count == 0) {
+		DEBUG(10, ("posix_lock_in_range: Count = 0. Ignoring lock "
+			   "u_offset = %ju, u_count = %ju\n",
+			   (uintmax_t)u_offset,
+			   (uintmax_t)u_count));
+		return False;
+	}
+
+	/*
+	 * The mapping was successful.
+	 */
+
+	DEBUG(10, ("posix_lock_in_range: offset_out = %ju, "
+		   "count_out = %ju\n",
+		   (uintmax_t)offset, (uintmax_t)count));
+
+	*offset_out = offset;
+	*count_out = count;
+	
+	return True;
+}
+
+bool smb_vfs_call_lock(struct vfs_handle_struct *handle,
+		       struct files_struct *fsp, int op, off_t offset,
+		       off_t count, int type)
+{
+	VFS_FIND(lock);
+	return handle->fns->lock_fn(handle, fsp, op, offset, count, type);
+}
+
+/****************************************************************************
+ Actual function that does POSIX locks. Copes with 64 -> 32 bit cruft and
+ broken NFS implementations.
+****************************************************************************/
+
+static bool posix_fcntl_lock(files_struct *fsp, int op, off_t offset, off_t count, int type)
+{
+	bool ret;
+
+	DEBUG(8,("posix_fcntl_lock %d %d %jd %jd %d\n",
+		 fsp_get_io_fd(fsp),op,(intmax_t)offset,(intmax_t)count,type));
+
+	ret = SMB_VFS_LOCK(fsp, op, offset, count, type);
+
+	if (!ret && ((errno == EFBIG) || (errno == ENOLCK) || (errno ==  EINVAL))) {
+
+		if ((errno == EINVAL) &&
+				(op != F_GETLK &&
+				 op != F_SETLK &&
+				 op != F_SETLKW)) {
+			DEBUG(0,("WARNING: OFD locks in use and no kernel "
+				"support. Try setting "
+				"'smbd:force process locks = true' "
+				"in smb.conf\n"));
+		} else {
+			DEBUG(0, ("WARNING: lock request at offset "
+			  "%ju, length %ju returned\n",
+			  (uintmax_t)offset, (uintmax_t)count));
+			DEBUGADD(0, ("an %s error. This can happen when using 64 bit "
+			     "lock offsets\n", strerror(errno)));
+			DEBUGADD(0, ("on 32 bit NFS mounted file systems.\n"));
+		}
+
+		/*
+		 * If the offset is > 0x7FFFFFFF then this will cause problems on
+		 * 32 bit NFS mounted filesystems. Just ignore it.
+		 */
+
+		if (offset & ~((off_t)0x7fffffff)) {
+			DEBUG(0,("Offset greater than 31 bits. Returning success.\n"));
+			return True;
+		}
+
+		if (count & ~((off_t)0x7fffffff)) {
+			/* 32 bit NFS file system, retry with smaller offset */
+			DEBUG(0,("Count greater than 31 bits - retrying with 31 bit truncated length.\n"));
+			errno = 0;
+			count &= 0x7fffffff;
+			ret = SMB_VFS_LOCK(fsp, op, offset, count, type);
+		}
+	}
+
+	DEBUG(8,("posix_fcntl_lock: Lock call %s\n", ret ? "successful" : "failed"));
+	return ret;
+}
+
+bool smb_vfs_call_getlock(struct vfs_handle_struct *handle,
+			  struct files_struct *fsp, off_t *poffset,
+			  off_t *pcount, int *ptype, pid_t *ppid)
+{
+	VFS_FIND(getlock);
+	return handle->fns->getlock_fn(handle, fsp, poffset, pcount, ptype, 
+				       ppid);
+}
+
+/****************************************************************************
+ Actual function that gets POSIX locks. Copes with 64 -> 32 bit cruft and
+ broken NFS implementations.
+****************************************************************************/
+
+static bool posix_fcntl_getlock(files_struct *fsp, off_t *poffset, off_t *pcount, int *ptype)
+{
+	pid_t pid;
+	bool ret;
+
+	DEBUG(8, ("posix_fcntl_getlock %d %ju %ju %d\n",
+		  fsp_get_io_fd(fsp), (uintmax_t)*poffset, (uintmax_t)*pcount,
+		  *ptype));
+
+	ret = SMB_VFS_GETLOCK(fsp, poffset, pcount, ptype, &pid);
+
+	if (!ret && ((errno == EFBIG) || (errno == ENOLCK) || (errno ==  EINVAL))) {
+
+		DEBUG(0, ("posix_fcntl_getlock: WARNING: lock request at "
+			  "offset %ju, length %ju returned\n",
+			  (uintmax_t)*poffset, (uintmax_t)*pcount));
+		DEBUGADD(0, ("an %s error. This can happen when using 64 bit "
+			     "lock offsets\n", strerror(errno)));
+		DEBUGADD(0, ("on 32 bit NFS mounted file systems.\n"));
+
+		/*
+		 * If the offset is > 0x7FFFFFFF then this will cause problems on
+		 * 32 bit NFS mounted filesystems. Just ignore it.
+		 */
+
+		if (*poffset & ~((off_t)0x7fffffff)) {
+			DEBUG(0,("Offset greater than 31 bits. Returning success.\n"));
+			return True;
+		}
+
+		if (*pcount & ~((off_t)0x7fffffff)) {
+			/* 32 bit NFS file system, retry with smaller offset */
+			DEBUG(0,("Count greater than 31 bits - retrying with 31 bit truncated length.\n"));
+			errno = 0;
+			*pcount &= 0x7fffffff;
+			ret = SMB_VFS_GETLOCK(fsp,poffset,pcount,ptype,&pid);
+		}
+	}
+
+	DEBUG(8,("posix_fcntl_getlock: Lock query call %s\n", ret ? "successful" : "failed"));
+	return ret;
+}
+
+/****************************************************************************
+ POSIX function to see if a file region is locked. Returns True if the
+ region is locked, False otherwise.
+****************************************************************************/
+
+bool is_posix_locked(files_struct *fsp,
+			uint64_t *pu_offset,
+			uint64_t *pu_count,
+			enum brl_type *plock_type,
+			enum brl_flavour lock_flav)
+{
+	off_t offset;
+	off_t count;
+	int posix_lock_type = map_posix_lock_type(fsp,*plock_type);
+
+	DEBUG(10, ("is_posix_locked: File %s, offset = %ju, count = %ju, "
+		   "type = %s\n", fsp_str_dbg(fsp), (uintmax_t)*pu_offset,
+		   (uintmax_t)*pu_count,  posix_lock_type_name(*plock_type)));
+
+	/*
+	 * If the requested lock won't fit in the POSIX range, we will
+	 * never set it, so presume it is not locked.
+	 */
+
+	if(!posix_lock_in_range(&offset, &count, *pu_offset, *pu_count)) {
+		return False;
+	}
+
+	if (!posix_fcntl_getlock(fsp,&offset,&count,&posix_lock_type)) {
+		return False;
+	}
+
+	if (posix_lock_type == F_UNLCK) {
+		return False;
+	}
+
+	if (lock_flav == POSIX_LOCK) {
+		/* Only POSIX lock queries need to know the details. */
+		*pu_offset = (uint64_t)offset;
+		*pu_count = (uint64_t)count;
+		*plock_type = (posix_lock_type == F_RDLCK) ? READ_LOCK : WRITE_LOCK;
+	}
+	return True;
+}
+
+/****************************************************************************
+ Next - the functions that deal with in memory database storing representations
+ of either Windows CIFS locks or POSIX CIFS locks.
+****************************************************************************/
+
+/* The key used in the in-memory POSIX databases. */
+
+struct lock_ref_count_key {
+	struct file_id id;
+	char r;
+}; 
+
+/*******************************************************************
+ Form a static locking key for a dev/inode pair for the lock ref count
+******************************************************************/
+
+static TDB_DATA locking_ref_count_key_fsp(const files_struct *fsp,
+					  struct lock_ref_count_key *tmp)
+{
+	ZERO_STRUCTP(tmp);
+	tmp->id = fsp->file_id;
+	tmp->r = 'r';
+	return make_tdb_data((uint8_t *)tmp, sizeof(*tmp));
+}
+
+/*******************************************************************
+ Convenience function to get an fd_array key from an fsp.
+******************************************************************/
+
+static TDB_DATA fd_array_key_fsp(const files_struct *fsp)
+{
+	return make_tdb_data((const uint8_t *)&fsp->file_id, sizeof(fsp->file_id));
+}
+
+/*******************************************************************
+ Create the in-memory POSIX lock databases.
+********************************************************************/
+
+bool posix_locking_init(bool read_only)
+{
+	if (posix_pending_close_db != NULL) {
+		return true;
+	}
+
+	posix_pending_close_db = db_open_rbt(NULL);
+
+	if (posix_pending_close_db == NULL) {
+		DEBUG(0,("Failed to open POSIX pending close database.\n"));
+		return false;
+	}
+
+	return true;
+}
+
+/*******************************************************************
+ Delete the in-memory POSIX lock databases.
+********************************************************************/
+
+bool posix_locking_end(void)
+{
+	/*
+	 * Shouldn't we close all fd's here?
+	 */
+	TALLOC_FREE(posix_pending_close_db);
+	return true;
+}
+
+/****************************************************************************
+ Next - the functions that deal with reference count of number of locks open
+ on a dev/ino pair.
+****************************************************************************/
+
+/****************************************************************************
+ Increase the lock ref count. Creates lock_ref_count entry if it doesn't exist.
+****************************************************************************/
+
+static void increment_lock_ref_count(const files_struct *fsp)
+{
+	struct lock_ref_count_key tmp;
+	int32_t lock_ref_count = 0;
+	NTSTATUS status;
+
+	status = dbwrap_change_int32_atomic(
+		posix_pending_close_db, locking_ref_count_key_fsp(fsp, &tmp),
+		&lock_ref_count, 1);
+
+	SMB_ASSERT(NT_STATUS_IS_OK(status));
+	SMB_ASSERT(lock_ref_count < INT32_MAX);
+
+	DEBUG(10,("lock_ref_count for file %s = %d\n",
+		  fsp_str_dbg(fsp), (int)(lock_ref_count + 1)));
+}
+
+/****************************************************************************
+ Reduce the lock ref count.
+****************************************************************************/
+
+static void decrement_lock_ref_count(const files_struct *fsp)
+{
+	struct lock_ref_count_key tmp;
+	int32_t lock_ref_count = 0;
+	NTSTATUS status;
+
+	status = dbwrap_change_int32_atomic(
+		posix_pending_close_db, locking_ref_count_key_fsp(fsp, &tmp),
+		&lock_ref_count, -1);
+
+	SMB_ASSERT(NT_STATUS_IS_OK(status));
+	SMB_ASSERT(lock_ref_count > 0);
+
+	DEBUG(10,("lock_ref_count for file %s = %d\n",
+		  fsp_str_dbg(fsp), (int)(lock_ref_count - 1)));
+}
+
+/****************************************************************************
+ Fetch the lock ref count.
+****************************************************************************/
+
+static int32_t get_lock_ref_count(const files_struct *fsp)
+{
+	struct lock_ref_count_key tmp;
+	NTSTATUS status;
+	int32_t lock_ref_count = 0;
+
+	status = dbwrap_fetch_int32(
+		posix_pending_close_db, locking_ref_count_key_fsp(fsp, &tmp),
+		&lock_ref_count);
+
+	if (!NT_STATUS_IS_OK(status) &&
+	    !NT_STATUS_EQUAL(status, NT_STATUS_NOT_FOUND)) {
+		DEBUG(0, ("Error fetching "
+			  "lock ref count for file %s: %s\n",
+			  fsp_str_dbg(fsp), nt_errstr(status)));
+	}
+	return lock_ref_count;
+}
+
+/****************************************************************************
+ Delete a lock_ref_count entry.
+****************************************************************************/
+
+static void delete_lock_ref_count(const files_struct *fsp)
+{
+	struct lock_ref_count_key tmp;
+
+	/* Not a bug if it doesn't exist - no locks were ever granted. */
+
+	dbwrap_delete(posix_pending_close_db,
+		      locking_ref_count_key_fsp(fsp, &tmp));
+
+	DEBUG(10,("delete_lock_ref_count for file %s\n",
+		  fsp_str_dbg(fsp)));
+}
+
+/****************************************************************************
+ Next - the functions that deal with storing fd's that have outstanding
+ POSIX locks when closed.
+****************************************************************************/
+
+/****************************************************************************
+ The records in posix_pending_close_db are composed of an array of
+ ints keyed by dev/ino pair. Those ints are the fd's that were open on
+ this dev/ino pair that should have been closed, but can't as the lock
+ ref count is non zero.
+****************************************************************************/
+
+struct add_fd_to_close_entry_state {
+	const struct files_struct *fsp;
+};
+
+static void add_fd_to_close_entry_fn(
+	struct db_record *rec,
+	TDB_DATA value,
+	void *private_data)
+{
+	struct add_fd_to_close_entry_state *state = private_data;
+	int fd = fsp_get_pathref_fd(state->fsp);
+	TDB_DATA values[] = {
+		value,
+		{ .dptr = (uint8_t *)&fd,
+		  .dsize = sizeof(fd) },
+	};
+	NTSTATUS status;
+
+	SMB_ASSERT((values[0].dsize % sizeof(int)) == 0);
+
+	status = dbwrap_record_storev(rec, values, ARRAY_SIZE(values), 0);
+	SMB_ASSERT(NT_STATUS_IS_OK(status));
+}
+
+/****************************************************************************
+ Add an fd to the pending close db.
+****************************************************************************/
+
+static void add_fd_to_close_entry(const files_struct *fsp)
+{
+	struct add_fd_to_close_entry_state state = { .fsp = fsp };
+	NTSTATUS status;
+
+	status = dbwrap_do_locked(
+		posix_pending_close_db,
+		fd_array_key_fsp(fsp),
+		add_fd_to_close_entry_fn,
+		&state);
+	SMB_ASSERT(NT_STATUS_IS_OK(status));
+
+	DBG_DEBUG("added fd %d file %s\n",
+		  fsp_get_pathref_fd(fsp),
+		  fsp_str_dbg(fsp));
+}
+
+static void fd_close_posix_fn(
+	struct db_record *rec,
+	TDB_DATA data,
+	void *private_data)
+{
+	size_t num_fds, i;
+
+	SMB_ASSERT((data.dsize % sizeof(int)) == 0);
+	num_fds = data.dsize / sizeof(int);
+
+	for (i=0; i<num_fds; i++) {
+		int fd;
+		memcpy(&fd, data.dptr, sizeof(int));
+		close(fd);
+		data.dptr += sizeof(int);
+	}
+	dbwrap_record_delete(rec);
+}
+
+/****************************************************************************
+ Deal with pending closes needed by POSIX locking support.
+ Note that locking_close_file() is expected to have been called
+ to delete all locks on this fsp before this function is called.
+****************************************************************************/
+
+int fd_close_posix(const struct files_struct *fsp)
+{
+	NTSTATUS status;
+
+	if (!lp_locking(fsp->conn->params) ||
+	    !lp_posix_locking(fsp->conn->params) ||
+	    fsp->fsp_flags.use_ofd_locks)
+	{
+		/*
+		 * No locking or POSIX to worry about or we are using POSIX
+		 * open file description lock semantics which only removes
+		 * locks on the file descriptor we're closing. Just close.
+		 */
+		return close(fsp_get_pathref_fd(fsp));
+	}
+
+	if (get_lock_ref_count(fsp)) {
+
+		/*
+		 * There are outstanding locks on this dev/inode pair on
+		 * other fds. Add our fd to the pending close db. We also
+		 * set fsp_get_io_fd(fsp) to -1 inside fd_close() after returning
+		 * from VFS layer.
+		 */
+
+		add_fd_to_close_entry(fsp);
+		return 0;
+	}
+
+	status = dbwrap_do_locked(
+		posix_pending_close_db,
+		fd_array_key_fsp(fsp),
+		fd_close_posix_fn,
+		NULL);
+	if (!NT_STATUS_IS_OK(status)) {
+		DBG_WARNING("dbwrap_do_locked failed: %s\n",
+			    nt_errstr(status));
+	}
+
+	/* Don't need a lock ref count on this dev/ino anymore. */
+	delete_lock_ref_count(fsp);
+
+	/*
+	 * Finally close the fd associated with this fsp.
+	 */
+
+	return close(fsp_get_pathref_fd(fsp));
+}
+
+/****************************************************************************
+ Next - the functions that deal with the mapping CIFS Windows locks onto
+ the underlying system POSIX locks.
+****************************************************************************/
+
+/*
+ * Structure used when splitting a lock range
+ * into a POSIX lock range. Doubly linked list.
+ */
+
+struct lock_list {
+	struct lock_list *next;
+	struct lock_list *prev;
+	off_t start;
+	off_t size;
+};
+
+/****************************************************************************
+ Create a list of lock ranges that don't overlap a given range. Used in calculating
+ POSIX locks and unlocks. This is a difficult function that requires ASCII art to
+ understand it :-).
+****************************************************************************/
+
+static struct lock_list *posix_lock_list(TALLOC_CTX *ctx,
+						struct lock_list *lhead,
+						const struct lock_context *lock_ctx, /* Lock context lhead belongs to. */
+						const struct lock_struct *plocks,
+						int num_locks)
+{
+	int i;
+
+	/*
+	 * Check the current lock list on this dev/inode pair.
+	 * Quit if the list is deleted.
+	 */
+
+	DEBUG(10, ("posix_lock_list: curr: start=%ju,size=%ju\n",
+		   (uintmax_t)lhead->start, (uintmax_t)lhead->size ));
+
+	for (i=0; i<num_locks && lhead; i++) {
+		const struct lock_struct *lock = &plocks[i];
+		struct lock_list *l_curr;
+
+		/* Ignore all but read/write locks. */
+		if (lock->lock_type != READ_LOCK && lock->lock_type != WRITE_LOCK) {
+			continue;
+		}
+
+		/* Ignore locks not owned by this process. */
+		if (!server_id_equal(&lock->context.pid, &lock_ctx->pid)) {
+			continue;
+		}
+
+		/*
+		 * Walk the lock list, checking for overlaps. Note that
+		 * the lock list can expand within this loop if the current
+		 * range being examined needs to be split.
+		 */
+
+		for (l_curr = lhead; l_curr;) {
+
+			DEBUG(10, ("posix_lock_list: lock: fnum=%ju: "
+				   "start=%ju,size=%ju:type=%s",
+				   (uintmax_t)lock->fnum,
+				   (uintmax_t)lock->start,
+				   (uintmax_t)lock->size,
+				   posix_lock_type_name(lock->lock_type) ));
+
+			if ( (l_curr->start >= (lock->start + lock->size)) ||
+				 (lock->start >= (l_curr->start + l_curr->size))) {
+
+				/* No overlap with existing lock - leave this range alone. */
+/*********************************************
+                                             +---------+
+                                             | l_curr  |
+                                             +---------+
+                                +-------+
+                                | lock  |
+                                +-------+
+OR....
+             +---------+
+             |  l_curr |
+             +---------+
+**********************************************/
+
+				DEBUG(10,(" no overlap case.\n" ));
+
+				l_curr = l_curr->next;
+
+			} else if ( (l_curr->start >= lock->start) &&
+						(l_curr->start + l_curr->size <= lock->start + lock->size) ) {
+
+				/*
+				 * This range is completely overlapped by this existing lock range
+				 * and thus should have no effect. Delete it from the list.
+				 */
+/*********************************************
+                +---------+
+                |  l_curr |
+                +---------+
+        +---------------------------+
+        |       lock                |
+        +---------------------------+
+**********************************************/
+				/* Save the next pointer */
+				struct lock_list *ul_next = l_curr->next;
+
+				DEBUG(10,(" delete case.\n" ));
+
+				DLIST_REMOVE(lhead, l_curr);
+				if(lhead == NULL) {
+					break; /* No more list... */
+				}
+
+				l_curr = ul_next;
+				
+			} else if ( (l_curr->start >= lock->start) &&
+						(l_curr->start < lock->start + lock->size) &&
+						(l_curr->start + l_curr->size > lock->start + lock->size) ) {
+
+				/*
+				 * This range overlaps the existing lock range at the high end.
+				 * Truncate by moving start to existing range end and reducing size.
+				 */
+/*********************************************
+                +---------------+
+                |  l_curr       |
+                +---------------+
+        +---------------+
+        |    lock       |
+        +---------------+
+BECOMES....
+                        +-------+
+                        | l_curr|
+                        +-------+
+**********************************************/
+
+				l_curr->size = (l_curr->start + l_curr->size) - (lock->start + lock->size);
+				l_curr->start = lock->start + lock->size;
+
+				DEBUG(10, (" truncate high case: start=%ju,"
+					   "size=%ju\n",
+					   (uintmax_t)l_curr->start,
+					   (uintmax_t)l_curr->size ));
+
+				l_curr = l_curr->next;
+
+			} else if ( (l_curr->start < lock->start) &&
+						(l_curr->start + l_curr->size > lock->start) &&
+						(l_curr->start + l_curr->size <= lock->start + lock->size) ) {
+
+				/*
+				 * This range overlaps the existing lock range at the low end.
+				 * Truncate by reducing size.
+				 */
+/*********************************************
+   +---------------+
+   |  l_curr       |
+   +---------------+
+           +---------------+
+           |    lock       |
+           +---------------+
+BECOMES....
+   +-------+
+   | l_curr|
+   +-------+
+**********************************************/
+
+				l_curr->size = lock->start - l_curr->start;
+
+				DEBUG(10, (" truncate low case: start=%ju,"
+					   "size=%ju\n",
+					   (uintmax_t)l_curr->start,
+					   (uintmax_t)l_curr->size ));
+
+				l_curr = l_curr->next;
+		
+			} else if ( (l_curr->start < lock->start) &&
+						(l_curr->start + l_curr->size > lock->start + lock->size) ) {
+				/*
+				 * Worst case scenario. Range completely overlaps an existing
+				 * lock range. Split the request into two, push the new (upper) request
+				 * into the dlink list, and continue with the entry after l_new (as we
+				 * know that l_new will not overlap with this lock).
+				 */
+/*********************************************
+        +---------------------------+
+        |        l_curr             |
+        +---------------------------+
+                +---------+
+                | lock    |
+                +---------+
+BECOMES.....
+        +-------+         +---------+
+        | l_curr|         | l_new   |
+        +-------+         +---------+
+**********************************************/
+				struct lock_list *l_new = talloc(ctx, struct lock_list);
+
+				if(l_new == NULL) {
+					DEBUG(0,("posix_lock_list: talloc fail.\n"));
+					return NULL; /* The talloc_destroy takes care of cleanup. */
+				}
+
+				ZERO_STRUCTP(l_new);
+				l_new->start = lock->start + lock->size;
+				l_new->size = l_curr->start + l_curr->size - l_new->start;
+
+				/* Truncate the l_curr. */
+				l_curr->size = lock->start - l_curr->start;
+
+				DEBUG(10, (" split case: curr: start=%ju,"
+					   "size=%ju new: start=%ju,"
+					   "size=%ju\n",
+					   (uintmax_t)l_curr->start,
+					   (uintmax_t)l_curr->size,
+					   (uintmax_t)l_new->start,
+					   (uintmax_t)l_new->size ));
+
+				/*
+				 * Add into the dlink list after the l_curr point - NOT at lhead. 
+				 */
+				DLIST_ADD_AFTER(lhead, l_new, l_curr);
+
+				/* And move after the link we added. */
+				l_curr = l_new->next;
+
+			} else {
+
+				/*
+				 * This logic case should never happen. Ensure this is the
+				 * case by forcing an abort.... Remove in production.
+				 */
+				char *msg = NULL;
+
+				if (asprintf(&msg, "logic flaw in cases: "
+					     "l_curr: start = %ju, "
+					     "size = %ju : lock: "
+					     "start = %ju, size = %ju",
+					     (uintmax_t)l_curr->start,
+					     (uintmax_t)l_curr->size,
+					     (uintmax_t)lock->start,
+					     (uintmax_t)lock->size ) != -1) {
+					smb_panic(msg);
+				} else {
+					smb_panic("posix_lock_list");
+				}
+			}
+		} /* end for ( l_curr = lhead; l_curr;) */
+	} /* end for (i=0; i<num_locks && ul_head; i++) */
+
+	return lhead;
+}
+
+/****************************************************************************
+ POSIX function to acquire a lock. Returns True if the
+ lock could be granted, False if not.
+****************************************************************************/
+
+bool set_posix_lock_windows_flavour(files_struct *fsp,
+			uint64_t u_offset,
+			uint64_t u_count,
+			enum brl_type lock_type,
+			const struct lock_context *lock_ctx,
+			const struct lock_struct *plocks,
+			int num_locks,
+			int *errno_ret)
+{
+	off_t offset;
+	off_t count;
+	int posix_lock_type = map_posix_lock_type(fsp,lock_type);
+	bool ret = True;
+	size_t lock_count;
+	TALLOC_CTX *l_ctx = NULL;
+	struct lock_list *llist = NULL;
+	struct lock_list *ll = NULL;
+
+	DEBUG(5, ("set_posix_lock_windows_flavour: File %s, offset = %ju, "
+		  "count = %ju, type = %s\n", fsp_str_dbg(fsp),
+		  (uintmax_t)u_offset, (uintmax_t)u_count,
+		  posix_lock_type_name(lock_type)));
+
+	/*
+	 * If the requested lock won't fit in the POSIX range, we will
+	 * pretend it was successful.
+	 */
+
+	if(!posix_lock_in_range(&offset, &count, u_offset, u_count)) {
+		increment_lock_ref_count(fsp);
+		return True;
+	}
+
+	/*
+	 * Windows is very strange. It allows read locks to be overlayed
+	 * (even over a write lock), but leaves the write lock in force until the first
+	 * unlock. It also reference counts the locks. This means the following sequence :
+	 *
+	 * process1                                      process2
+	 * ------------------------------------------------------------------------
+	 * WRITE LOCK : start = 2, len = 10
+	 *                                            READ LOCK: start =0, len = 10 - FAIL
+	 * READ LOCK : start = 0, len = 14 
+	 *                                            READ LOCK: start =0, len = 10 - FAIL
+	 * UNLOCK : start = 2, len = 10
+	 *                                            READ LOCK: start =0, len = 10 - OK
+	 *
+	 * Under POSIX, the same sequence in steps 1 and 2 would not be reference counted, but
+	 * would leave a single read lock over the 0-14 region.
+	 */
+	
+	if ((l_ctx = talloc_init("set_posix_lock")) == NULL) {
+		DEBUG(0,("set_posix_lock_windows_flavour: unable to init talloc context.\n"));
+		return False;
+	}
+
+	if ((ll = talloc(l_ctx, struct lock_list)) == NULL) {
+		DEBUG(0,("set_posix_lock_windows_flavour: unable to talloc unlock list.\n"));
+		talloc_destroy(l_ctx);
+		return False;
+	}
+
+	/*
+	 * Create the initial list entry containing the
+	 * lock we want to add.
+	 */
+
+	ZERO_STRUCTP(ll);
+	ll->start = offset;
+	ll->size = count;
+
+	DLIST_ADD(llist, ll);
+
+	/*
+	 * The following call calculates if there are any
+	 * overlapping locks held by this process on
+	 * fd's open on the same file and splits this list
+	 * into a list of lock ranges that do not overlap with existing
+	 * POSIX locks.
+	 */
+
+	llist = posix_lock_list(l_ctx,
+				llist,
+				lock_ctx, /* Lock context llist belongs to. */
+				plocks,
+				num_locks);
+
+	/*
+	 * Add the POSIX locks on the list of ranges returned.
+	 * As the lock is supposed to be added atomically, we need to
+	 * back out all the locks if any one of these calls fail.
+	 */
+
+	for (lock_count = 0, ll = llist; ll; ll = ll->next, lock_count++) {
+		offset = ll->start;
+		count = ll->size;
+
+		DEBUG(5, ("set_posix_lock_windows_flavour: Real lock: "
+			  "Type = %s: offset = %ju, count = %ju\n",
+			  posix_lock_type_name(posix_lock_type),
+			  (uintmax_t)offset, (uintmax_t)count ));
+
+		if (!posix_fcntl_lock(fsp,F_SETLK,offset,count,posix_lock_type)) {
+			*errno_ret = errno;
+			DEBUG(5, ("set_posix_lock_windows_flavour: Lock "
+				  "fail !: Type = %s: offset = %ju, "
+				  "count = %ju. Errno = %s\n",
+				  posix_lock_type_name(posix_lock_type),
+				  (uintmax_t)offset, (uintmax_t)count,
+				  strerror(errno) ));
+			ret = False;
+			break;
+		}
+	}
+
+	if (!ret) {
+
+		/*
+		 * Back out all the POSIX locks we have on fail.
+		 */
+
+		for (ll = llist; lock_count; ll = ll->next, lock_count--) {
+			offset = ll->start;
+			count = ll->size;
+
+			DEBUG(5, ("set_posix_lock_windows_flavour: Backing "
+				  "out locks: Type = %s: offset = %ju, "
+				  "count = %ju\n",
+				  posix_lock_type_name(posix_lock_type),
+				  (uintmax_t)offset, (uintmax_t)count ));
+
+			posix_fcntl_lock(fsp,F_SETLK,offset,count,F_UNLCK);
+		}
+	} else {
+		/* Remember the number of locks we have on this dev/ino pair. */
+		increment_lock_ref_count(fsp);
+	}
+
+	talloc_destroy(l_ctx);
+	return ret;
+}
+
+/****************************************************************************
+ POSIX function to release a lock. Returns True if the
+ lock could be released, False if not.
+****************************************************************************/
+
+bool release_posix_lock_windows_flavour(files_struct *fsp,
+				uint64_t u_offset,
+				uint64_t u_count,
+				enum brl_type deleted_lock_type,
+				const struct lock_context *lock_ctx,
+				const struct lock_struct *plocks,
+				int num_locks)
+{
+	off_t offset;
+	off_t count;
+	bool ret = True;
+	TALLOC_CTX *ul_ctx = NULL;
+	struct lock_list *ulist = NULL;
+	struct lock_list *ul = NULL;
+
+	DEBUG(5, ("release_posix_lock_windows_flavour: File %s, offset = %ju, "
+		  "count = %ju\n", fsp_str_dbg(fsp),
+		  (uintmax_t)u_offset, (uintmax_t)u_count));
+
+	/* Remember the number of locks we have on this dev/ino pair. */
+	decrement_lock_ref_count(fsp);
+
+	/*
+	 * If the requested lock won't fit in the POSIX range, we will
+	 * pretend it was successful.
+	 */
+
+	if(!posix_lock_in_range(&offset, &count, u_offset, u_count)) {
+		return True;
+	}
+
+	if ((ul_ctx = talloc_init("release_posix_lock")) == NULL) {
+		DEBUG(0,("release_posix_lock_windows_flavour: unable to init talloc context.\n"));
+		return False;
+	}
+
+	if ((ul = talloc(ul_ctx, struct lock_list)) == NULL) {
+		DEBUG(0,("release_posix_lock_windows_flavour: unable to talloc unlock list.\n"));
+		talloc_destroy(ul_ctx);
+		return False;
+	}
+
+	/*
+	 * Create the initial list entry containing the
+	 * lock we want to remove.
+	 */
+
+	ZERO_STRUCTP(ul);
+	ul->start = offset;
+	ul->size = count;
+
+	DLIST_ADD(ulist, ul);
+
+	/*
+	 * The following call calculates if there are any
+	 * overlapping locks held by this process on
+	 * fd's open on the same file and creates a
+	 * list of unlock ranges that will allow
+	 * POSIX lock ranges to remain on the file whilst the
+	 * unlocks are performed.
+	 */
+
+	ulist = posix_lock_list(ul_ctx,
+				ulist,
+				lock_ctx, /* Lock context ulist belongs to. */
+				plocks,
+				num_locks);
+
+	/*
+	 * If there were any overlapped entries (list is > 1 or size or start have changed),
+	 * and the lock_type we just deleted from
+	 * the upper layer tdb was a write lock, then before doing the unlock we need to downgrade
+	 * the POSIX lock to a read lock. This allows any overlapping read locks
+	 * to be atomically maintained.
+	 */
+
+	if (deleted_lock_type == WRITE_LOCK &&
+			(!ulist || ulist->next != NULL || ulist->start != offset || ulist->size != count)) {
+
+		DEBUG(5, ("release_posix_lock_windows_flavour: downgrading "
+			  "lock to READ: offset = %ju, count = %ju\n",
+			  (uintmax_t)offset, (uintmax_t)count ));
+
+		if (!posix_fcntl_lock(fsp,F_SETLK,offset,count,F_RDLCK)) {
+			DEBUG(0,("release_posix_lock_windows_flavour: downgrade of lock failed with error %s !\n", strerror(errno) ));
+			talloc_destroy(ul_ctx);
+			return False;
+		}
+	}
+
+	/*
+	 * Release the POSIX locks on the list of ranges returned.
+	 */
+
+	for(; ulist; ulist = ulist->next) {
+		offset = ulist->start;
+		count = ulist->size;
+
+		DEBUG(5, ("release_posix_lock_windows_flavour: Real unlock: "
+			  "offset = %ju, count = %ju\n",
+			  (uintmax_t)offset, (uintmax_t)count ));
+
+		if (!posix_fcntl_lock(fsp,F_SETLK,offset,count,F_UNLCK)) {
+			ret = False;
+		}
+	}
+
+	talloc_destroy(ul_ctx);
+	return ret;
+}
+
+/****************************************************************************
+ Next - the functions that deal with mapping CIFS POSIX locks onto
+ the underlying system POSIX locks.
+****************************************************************************/
+
+/****************************************************************************
+ We only increment the lock ref count when we see a POSIX lock on a context
+ that doesn't already have them.
+****************************************************************************/
+
+static void increment_posix_lock_count(const files_struct *fsp,
+					uint64_t smblctx)
+{
+	NTSTATUS status;
+	TDB_DATA ctx_key;
+	TDB_DATA val = { 0 };
+
+	ctx_key.dptr = (uint8_t *)&smblctx;
+	ctx_key.dsize = sizeof(smblctx);
+
+	/*
+	 * Don't increment if we already have any POSIX flavor
+	 * locks on this context.
+	 */
+	if (dbwrap_exists(posix_pending_close_db, ctx_key)) {
+		return;
+	}
+
+	/* Remember that we have POSIX flavor locks on this context. */
+	status = dbwrap_store(posix_pending_close_db, ctx_key, val, 0);
+	SMB_ASSERT(NT_STATUS_IS_OK(status));
+
+	increment_lock_ref_count(fsp);
+
+	DEBUG(10,("posix_locks set for file %s\n",
+		fsp_str_dbg(fsp)));
+}
+
+static void decrement_posix_lock_count(const files_struct *fsp, uint64_t smblctx)
+{
+	NTSTATUS status;
+	TDB_DATA ctx_key;
+
+	ctx_key.dptr = (uint8_t *)&smblctx;
+	ctx_key.dsize = sizeof(smblctx);
+
+	status = dbwrap_delete(posix_pending_close_db, ctx_key);
+	SMB_ASSERT(NT_STATUS_IS_OK(status));
+
+	decrement_lock_ref_count(fsp);
+
+	DEBUG(10,("posix_locks deleted for file %s\n",
+		fsp_str_dbg(fsp)));
+}
+
+/****************************************************************************
+ Return true if any locks exist on the given lock context.
+****************************************************************************/
+
+static bool locks_exist_on_context(const struct lock_struct *plocks,
+				int num_locks,
+				const struct lock_context *lock_ctx)
+{
+	int i;
+
+	for (i=0; i < num_locks; i++) {
+		const struct lock_struct *lock = &plocks[i];
+
+		/* Ignore all but read/write locks. */
+		if (lock->lock_type != READ_LOCK && lock->lock_type != WRITE_LOCK) {
+			continue;
+		}
+
+		/* Ignore locks not owned by this process. */
+		if (!server_id_equal(&lock->context.pid, &lock_ctx->pid)) {
+			continue;
+		}
+
+		if (lock_ctx->smblctx == lock->context.smblctx) {
+			return true;
+		}
+	}
+	return false;
+}
+
+/****************************************************************************
+ POSIX function to acquire a lock. Returns True if the
+ lock could be granted, False if not.
+ As POSIX locks don't stack or conflict (they just overwrite)
+ we can map the requested lock directly onto a system one. We
+ know it doesn't conflict with locks on other contexts as the
+ upper layer would have refused it.
+****************************************************************************/
+
+bool set_posix_lock_posix_flavour(files_struct *fsp,
+			uint64_t u_offset,
+			uint64_t u_count,
+			enum brl_type lock_type,
+			const struct lock_context *lock_ctx,
+			int *errno_ret)
+{
+	off_t offset;
+	off_t count;
+	int posix_lock_type = map_posix_lock_type(fsp,lock_type);
+
+	DEBUG(5,("set_posix_lock_posix_flavour: File %s, offset = %ju, count "
+		 "= %ju, type = %s\n", fsp_str_dbg(fsp),
+		 (uintmax_t)u_offset, (uintmax_t)u_count,
+		 posix_lock_type_name(lock_type)));
+
+	/*
+	 * If the requested lock won't fit in the POSIX range, we will
+	 * pretend it was successful.
+	 */
+
+	if(!posix_lock_in_range(&offset, &count, u_offset, u_count)) {
+		increment_posix_lock_count(fsp, lock_ctx->smblctx);
+		return True;
+	}
+
+	if (!posix_fcntl_lock(fsp,F_SETLK,offset,count,posix_lock_type)) {
+		*errno_ret = errno;
+		DEBUG(5,("set_posix_lock_posix_flavour: Lock fail !: Type = %s: offset = %ju, count = %ju. Errno = %s\n",
+			posix_lock_type_name(posix_lock_type), (intmax_t)offset, (intmax_t)count, strerror(errno) ));
+		return False;
+	}
+	increment_posix_lock_count(fsp, lock_ctx->smblctx);
+	return True;
+}
+
+/****************************************************************************
+ POSIX function to release a lock. Returns True if the
+ lock could be released, False if not.
+ We are given a complete lock state from the upper layer which is what the lock
+ state should be after the unlock has already been done, so what
+ we do is punch out holes in the unlock range where locks owned by this process
+ have a different lock context.
+****************************************************************************/
+
+bool release_posix_lock_posix_flavour(files_struct *fsp,
+				uint64_t u_offset,
+				uint64_t u_count,
+				const struct lock_context *lock_ctx,
+				const struct lock_struct *plocks,
+				int num_locks)
+{
+	bool ret = True;
+	off_t offset;
+	off_t count;
+	TALLOC_CTX *ul_ctx = NULL;
+	struct lock_list *ulist = NULL;
+	struct lock_list *ul = NULL;
+
+	DEBUG(5, ("release_posix_lock_posix_flavour: File %s, offset = %ju, "
+		  "count = %ju\n", fsp_str_dbg(fsp),
+		  (uintmax_t)u_offset, (uintmax_t)u_count));
+
+	/*
+	 * If the requested lock won't fit in the POSIX range, we will
+	 * pretend it was successful.
+	 */
+
+	if(!posix_lock_in_range(&offset, &count, u_offset, u_count)) {
+		if (!locks_exist_on_context(plocks, num_locks, lock_ctx)) {
+			decrement_posix_lock_count(fsp, lock_ctx->smblctx);
+		}
+		return True;
+	}
+
+	if ((ul_ctx = talloc_init("release_posix_lock")) == NULL) {
+		DEBUG(0,("release_posix_lock_windows_flavour: unable to init talloc context.\n"));
+		return False;
+	}
+
+	if ((ul = talloc(ul_ctx, struct lock_list)) == NULL) {
+		DEBUG(0,("release_posix_lock_windows_flavour: unable to talloc unlock list.\n"));
+		talloc_destroy(ul_ctx);
+		return False;
+	}
+
+	/*
+	 * Create the initial list entry containing the
+	 * lock we want to remove.
+	 */
+
+	ZERO_STRUCTP(ul);
+	ul->start = offset;
+	ul->size = count;
+
+	DLIST_ADD(ulist, ul);
+
+	/*
+	 * Walk the given array creating a linked list
+	 * of unlock requests.
+	 */
+
+	ulist = posix_lock_list(ul_ctx,
+				ulist,
+				lock_ctx, /* Lock context ulist belongs to. */
+				plocks,
+				num_locks);
+
+	/*
+	 * Release the POSIX locks on the list of ranges returned.
+	 */
+
+	for(; ulist; ulist = ulist->next) {
+		offset = ulist->start;
+		count = ulist->size;
+
+		DEBUG(5, ("release_posix_lock_posix_flavour: Real unlock: "
+			  "offset = %ju, count = %ju\n",
+			  (uintmax_t)offset, (uintmax_t)count ));
+
+		if (!posix_fcntl_lock(fsp,F_SETLK,offset,count,F_UNLCK)) {
+			ret = False;
+		}
+	}
+
+	if (!locks_exist_on_context(plocks, num_locks, lock_ctx)) {
+		decrement_posix_lock_count(fsp, lock_ctx->smblctx);
+	}
+	talloc_destroy(ul_ctx);
+	return ret;
+}