diff -rudb ceph-0.91.orig/src/client/Client.cc ceph-0.91/src/client/Client.cc
--- ceph-0.91.orig/src/client/Client.cc	2015-01-14 00:42:08.000000000 +0100
+++ ceph-0.91/src/client/Client.cc	2015-02-06 15:18:50.231912657 +0100
@@ -5665,6 +5665,19 @@
   return _setattr(in, &attr, CEPH_SETATTR_MTIME|CEPH_SETATTR_ATIME);
 }
 
+int Client::flock(int fd, int operation, uint64_t owner)
+{
+  Mutex::Locker lock(client_lock);
+  tout(cct) << "flock" << std::endl;
+  tout(cct) << fd << std::endl;
+  tout(cct) << operation << std::endl;
+  Fh *f = get_filehandle(fd);
+  if (!f)
+    return -EBADF;
+
+  return _flock(f, operation, owner, NULL);
+}
+
 int Client::opendir(const char *relpath, dir_result_t **dirpp) 
 {
   Mutex::Locker lock(client_lock);
diff -rudb ceph-0.91.orig/src/client/Client.h ceph-0.91/src/client/Client.h
--- ceph-0.91.orig/src/client/Client.h	2015-01-14 00:42:08.000000000 +0100
+++ ceph-0.91/src/client/Client.h	2015-02-06 14:47:28.894246885 +0100
@@ -813,6 +813,7 @@
   int lchown(const char *path, int uid, int gid);
   int utime(const char *path, struct utimbuf *buf);
   int lutime(const char *path, struct utimbuf *buf);
+  int flock(int fd, int operation, uint64_t owner);
   int truncate(const char *path, loff_t size);
 
   // file ops
diff -rudb ceph-0.91.orig/src/include/cephfs/libcephfs.h ceph-0.91/src/include/cephfs/libcephfs.h
--- ceph-0.91.orig/src/include/cephfs/libcephfs.h	2015-01-14 00:42:04.000000000 +0100
+++ ceph-0.91/src/include/cephfs/libcephfs.h	2015-02-06 14:48:35.013737212 +0100
@@ -684,6 +684,21 @@
 int ceph_utime(struct ceph_mount_info *cmount, const char *path, struct utimbuf *buf);
 
 /**
+ * Apply or remove an advisory lock.
+ *
+ * @param cmount the ceph mount handle to use for performing the utime.
+ * @param fd the open file descriptor to change advisory lock.
+ * @param operation the advisory lock operation to be performed on the file
+ * descriptor among LOCK_SH (shared lock), LOCK_EX (exclusive lock),
+ * or LOCK_UN (remove lock). The LOCK_NB value can be ORed to perform a
+ * non-blocking operation.
+ * @param owner the user-supplied owner identifier
+ * @returns 0 on success or negative error code on failure.
+ */
+int ceph_flock(struct ceph_mount_info *cmount, int fd, int operation,
+	       uint64_t owner);
+
+/**
  * Truncate the file to the given size.  If this operation causes the
  * file to expand, the empty bytes will be filled in with zeros.
  *
diff -rudb ceph-0.91.orig/src/libcephfs.cc ceph-0.91/src/libcephfs.cc
--- ceph-0.91.orig/src/libcephfs.cc	2015-01-14 00:42:04.000000000 +0100
+++ ceph-0.91/src/libcephfs.cc	2015-02-06 14:47:50.626079362 +0100
@@ -718,6 +718,14 @@
   return cmount->get_client()->utime(path, buf);
 }
 
+extern "C" int ceph_flock(struct ceph_mount_info *cmount, int fd, int operation,
+			  uint64_t owner)
+{
+  if (!cmount->is_mounted())
+    return -ENOTCONN;
+  return cmount->get_client()->flock(fd, operation, owner);
+}
+
 extern "C" int ceph_truncate(struct ceph_mount_info *cmount, const char *path,
 			     int64_t size)
 {