--- source3/modules/gpfs.c.orig	2010-06-19 10:17:18.000000000 +0200
+++ source3/modules/gpfs.c	2010-06-19 10:21:54.000000000 +0200
@@ -28,6 +28,7 @@
 static bool gpfs_leases;
 static bool gpfs_getrealfilename;
 static bool gpfs_winattr;
+static bool gpfs_do_ftruncate;
 
 static int (*gpfs_set_share_fn)(int fd, unsigned int allow, unsigned int deny);
 static int (*gpfs_set_lease_fn)(int fd, unsigned int leaseType);
@@ -38,7 +39,7 @@
 static int (*gpfs_set_winattrs_path_fn)(char *pathname, int flags, struct gpfs_winattr *attrs);
 static int (*gpfs_get_winattrs_path_fn)(char *pathname, struct gpfs_winattr *attrs);
 static int (*gpfs_get_winattrs_fn)(int fd, struct gpfs_winattr *attrs);
-
+static int (*gpfs_ftruncate_fn)(int fd, gpfs_off64_t length);
 
 bool set_gpfs_sharemode(files_struct *fsp, uint32 access_mask,
 			uint32 share_access)
@@ -141,6 +142,16 @@
 	return gpfs_putacl_fn(pathname, flags, acl);
 }
 
+int smbd_gpfs_ftrunctate(int fd, gpfs_off64_t length)
+{
+       if (!gpfs_do_ftruncate || (gpfs_ftruncate_fn == NULL)) {
+               errno = ENOSYS;
+               return -1;
+       }
+
+       return gpfs_ftruncate_fn(fd, length);
+}
+
 int smbd_gpfs_get_realfilename_path(char *pathname, char *filenamep,
 				    int *buflen)
 {
@@ -247,7 +258,7 @@
 	init_gpfs_function(&gpfs_get_winattrs_path_fn,"gpfs_get_winattrs_path");
         init_gpfs_function(&gpfs_set_winattrs_path_fn,"gpfs_set_winattrs_path");
         init_gpfs_function(&gpfs_get_winattrs_fn,"gpfs_get_winattrs");
-
+	init_gpfs_function(&gpfs_ftruncate_fn,"gpfs_ftruncate");
 
 	gpfs_share_modes = lp_parm_bool(-1, "gpfs", "sharemodes", True);
 	gpfs_leases      = lp_parm_bool(-1, "gpfs", "leases", True);
@@ -255,6 +266,8 @@
 					    True);
 	gpfs_winattr = lp_parm_bool(-1, "gpfs", "winattr", False);
 
+	gpfs_do_ftruncate = lp_parm_bool(-1, "gpfs", "ftruncate", True);
+
 	return;
 }
 
--- source3/modules/vfs_gpfs.c.orig	2010-06-19 10:17:31.000000000 +0200
+++ source3/modules/vfs_gpfs.c	2010-06-19 10:31:54.000000000 +0200
@@ -1103,6 +1103,19 @@
 
 }
 
+static int vfs_gpfs_ftruncate(struct vfs_handle_struct *handle,
+                              struct files_struct *fsp,
+                              SMB_OFF_T len)
+{
+       int result;
+
+       result = smbd_gpfs_ftrunctate(fsp->fh->fd, len);
+       if ((result == -1) && (errno == ENOSYS)) {
+               return SMB_VFS_NEXT_FTRUNCATE(handle, fsp, len);
+       }
+       return result;
+}
+
 static struct vfs_fn_pointers vfs_gpfs_fns = {
 	.kernel_flock = vfs_gpfs_kernel_flock,
         .linux_setlease = vfs_gpfs_setlease,
@@ -1124,6 +1137,7 @@
         .fstat = vfs_gpfs_fstat,
         .lstat = vfs_gpfs_lstat,
 	.ntimes = vfs_gpfs_ntimes,
+	.ftruncate = vfs_gpfs_ftruncate,
 };
 
 NTSTATUS vfs_gpfs_init(void);
--- source3/modules/vfs_gpfs.h.orig	2010-06-19 10:17:37.000000000 +0200
+++ source3/modules/vfs_gpfs.h	2010-06-19 10:32:40.000000000 +0200
@@ -34,4 +34,5 @@
 int smbd_fget_gpfs_winattrs(int fd, struct gpfs_winattr *attrs);
 int get_gpfs_winattrs(char * pathname,struct gpfs_winattr *attrs);
 int set_gpfs_winattrs(char * pathname,int flags,struct gpfs_winattr *attrs);
+int smbd_gpfs_ftrunctate(int fd, gpfs_off64_t length);
 void init_gpfs(void);