Set cwd to '/' for the process executing insmod.

Ricardo has pointed out that under Solaris the cwd is set to '/'
during module load, while under Linux it is set to the callers cwd.
To handle this cleanly I've reworked the module *_init()/_exit()
macros so they call a *_setup()/_cleanup() function when any SPL
dependent module is loaded or unloaded.  This gives us a chance to
perform any needed modification of the process, in this case changing
the cwd.  It also handily provides a way to avoid creating wrapper
init()/exit() functions because the Solaris and Linux prototypes
differ slightly.  All dependent modules should now call the spl
helper macros spl_module_{init,exit}() instead of the native linux
versions.

Unfortunately, it appears that under Linux there has been no consistent
API in the kernel to set the cwd in a module.  Because of this I have
had to add more autoconf magic than I'd like.  However, what I have
done is correct and has been tested on RHEL5, SLES11, FC11, and CHAOS
kernels.

In addition, I have change the rootdir type from a 'void *' to the
correct 'vnode_t *' type.  And I've set rootdir to a non-NULL value.

10 files changed, 404 insertions, 8 deletions

diff --git a/config/spl-build.m4 b/config/spl-build.m4
index 3293aa273..e6a626108 100644
--- a/config/spl-build.m4
+++ b/config/spl-build.m4
@@ -64,6 +64,8 @@ AC_DEFUN([SPL_AC_CONFIG_KERNEL], [
 	SPL_AC_ZONE_STAT_ITEM_INACTIVE
 	SPL_AC_ZONE_STAT_ITEM_ACTIVE
 	SPL_AC_GET_ZONE_COUNTS
+	SPL_AC_SET_FS_PWD
+	SPL_AC_2ARGS_SET_FS_PWD
 	SPL_AC_2ARGS_VFS_UNLINK
 	SPL_AC_4ARGS_VFS_RENAME
 	SPL_AC_CRED_STRUCT
@@ -1204,6 +1206,37 @@ AC_DEFUN([SPL_AC_GET_ZONE_COUNTS], [
 ])
 
 dnl #
+dnl # Symbol available in RHEL kernels not in stock kernels.
+dnl #
+AC_DEFUN([SPL_AC_SET_FS_PWD], [
+	SPL_CHECK_SYMBOL_EXPORT(
+		[set_fs_pwd],
+		[],
+		[AC_DEFINE(HAVE_SET_FS_PWD, 1,
+		[set_fs_pwd() is available])],
+		[])
+])
+
+dnl #
+dnl # 2.6.25 API change,
+dnl # Simplied API by replacing mnt+dentry args with a single path arg.
+dnl #
+AC_DEFUN([SPL_AC_2ARGS_SET_FS_PWD],
+	[AC_MSG_CHECKING([whether set_fs_pwd() wants 2 args])
+	SPL_LINUX_TRY_COMPILE([
+		#include <linux/sched.h>
+	],[
+		set_fs_pwd(NULL, NULL);
+	],[
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_2ARGS_SET_FS_PWD, 1,
+		          [set_fs_pwd() wants 2 args])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
+
+dnl #
 dnl # SLES API change, never adopted in mainline,
 dnl # Third 'struct vfsmount *' argument removed.
 dnl #
diff --git a/configure b/configure
index 03b23036e..8c8736883 100755
--- a/configure
+++ b/configure
@@ -21715,6 +21715,111 @@ fi
 
 
 
+
+	echo "$as_me:$LINENO: checking whether symbol set_fs_pwd is exported" >&5
+echo $ECHO_N "checking whether symbol set_fs_pwd is exported... $ECHO_C" >&6
+	grep -q -E '[[:space:]]set_fs_pwd[[:space:]]' \
+		$LINUX_OBJ/Module*.symvers 2>/dev/null
+	rc=$?
+	if test $rc -ne 0; then
+		export=0
+		for file in ; do
+			grep -q -E "EXPORT_SYMBOL.*(set_fs_pwd)" \
+				"$LINUX_OBJ/$file" 2>/dev/null
+			rc=$?
+		        if test $rc -eq 0; then
+		                export=1
+		                break;
+		        fi
+		done
+		if test $export -eq 0; then
+			echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6
+
+		else
+			echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_SET_FS_PWD 1
+_ACEOF
+
+		fi
+	else
+		echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_SET_FS_PWD 1
+_ACEOF
+
+	fi
+
+
+	echo "$as_me:$LINENO: checking whether set_fs_pwd() wants 2 args" >&5
+echo $ECHO_N "checking whether set_fs_pwd() wants 2 args... $ECHO_C" >&6
+
+
+cat >conftest.c <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+
+		#include <linux/sched.h>
+
+int
+main (void)
+{
+
+		set_fs_pwd(NULL, NULL);
+
+  ;
+  return 0;
+}
+
+_ACEOF
+
+
+	rm -Rf build && mkdir -p build
+	echo "obj-m := conftest.o" >build/Makefile
+	if { ac_try='cp conftest.c build && make modules -C $LINUX_OBJ EXTRA_CFLAGS="-Werror-implicit-function-declaration $EXTRA_KCFLAGS" $ARCH_UM M=$PWD/build'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } >/dev/null && { ac_try='test -s build/conftest.o'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+
+		echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_2ARGS_SET_FS_PWD 1
+_ACEOF
+
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+		echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6
+
+
+
+fi
+
+	rm -Rf build
+
+
+
 	echo "$as_me:$LINENO: checking whether vfs_unlink() wants 2 args" >&5
 echo $ECHO_N "checking whether vfs_unlink() wants 2 args... $ECHO_C" >&6
 
@@ -24758,6 +24863,111 @@ fi
 
 
 
+
+	echo "$as_me:$LINENO: checking whether symbol set_fs_pwd is exported" >&5
+echo $ECHO_N "checking whether symbol set_fs_pwd is exported... $ECHO_C" >&6
+	grep -q -E '[[:space:]]set_fs_pwd[[:space:]]' \
+		$LINUX_OBJ/Module*.symvers 2>/dev/null
+	rc=$?
+	if test $rc -ne 0; then
+		export=0
+		for file in ; do
+			grep -q -E "EXPORT_SYMBOL.*(set_fs_pwd)" \
+				"$LINUX_OBJ/$file" 2>/dev/null
+			rc=$?
+		        if test $rc -eq 0; then
+		                export=1
+		                break;
+		        fi
+		done
+		if test $export -eq 0; then
+			echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6
+
+		else
+			echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_SET_FS_PWD 1
+_ACEOF
+
+		fi
+	else
+		echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_SET_FS_PWD 1
+_ACEOF
+
+	fi
+
+
+	echo "$as_me:$LINENO: checking whether set_fs_pwd() wants 2 args" >&5
+echo $ECHO_N "checking whether set_fs_pwd() wants 2 args... $ECHO_C" >&6
+
+
+cat >conftest.c <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+
+		#include <linux/sched.h>
+
+int
+main (void)
+{
+
+		set_fs_pwd(NULL, NULL);
+
+  ;
+  return 0;
+}
+
+_ACEOF
+
+
+	rm -Rf build && mkdir -p build
+	echo "obj-m := conftest.o" >build/Makefile
+	if { ac_try='cp conftest.c build && make modules -C $LINUX_OBJ EXTRA_CFLAGS="-Werror-implicit-function-declaration $EXTRA_KCFLAGS" $ARCH_UM M=$PWD/build'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } >/dev/null && { ac_try='test -s build/conftest.o'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+
+		echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_2ARGS_SET_FS_PWD 1
+_ACEOF
+
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+		echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6
+
+
+
+fi
+
+	rm -Rf build
+
+
+
 	echo "$as_me:$LINENO: checking whether vfs_unlink() wants 2 args" >&5
 echo $ECHO_N "checking whether vfs_unlink() wants 2 args... $ECHO_C" >&6
 
diff --git a/include/linux/module_compat.h b/include/linux/module_compat.h
new file mode 100644
index 000000000..766cb58ea
--- /dev/null
+++ b/include/linux/module_compat.h
@@ -0,0 +1,35 @@
+#ifndef _SPL_MODULE_COMPAT_H
+#define _SPL_MODULE_COMPAT_H
+
+#include <linux/module.h>
+
+#define spl_module_init(init_fn)                                        \
+static int                                                              \
+spl_##init_fn(void)                                                     \
+{                                                                       \
+	int rc;                                                         \
+	                                                                \
+	spl_setup();                                                    \
+	rc = init_fn();                                                 \
+                                                                        \
+	return rc;                                                      \
+}                                                                       \
+                                                                        \
+module_init(spl_##init_fn)
+
+#define spl_module_exit(exit_fn)                                        \
+static void                                                             \
+spl_##exit_fn(void)                                                     \
+{                                                                       \
+	int rc;                                                         \
+                                                                        \
+	rc = exit_fn();                                                 \
+	spl_cleanup();                                                  \
+	if (rc)                                                         \
+		printk(KERN_ERR "SPL: Failure %d unloading "            \
+		       "dependent module\n", rc);                       \
+}                                                                       \
+                                                                        \
+module_exit(spl_##exit_fn)
+
+#endif /* _SPL_MODULE_COMPAT_H */
diff --git a/include/sys/sysmacros.h b/include/sys/sysmacros.h
index 67afbfeb0..e66d8d991 100644
--- a/include/sys/sysmacros.h
+++ b/include/sys/sysmacros.h
@@ -144,6 +144,8 @@ extern int p0;
 /* Missing misc functions */
 extern int highbit(unsigned long i);
 extern uint32_t zone_get_hostid(void *zone);
+extern void spl_setup(void);
+extern void spl_cleanup(void);
 
 #define makedevice(maj,min) makedev(maj,min)
 
diff --git a/include/sys/types.h b/include/sys/types.h
index 252def7bd..89cf115c0 100644
--- a/include/sys/types.h
+++ b/include/sys/types.h
@@ -18,6 +18,7 @@ extern "C" {
 #include <linux/workqueue_compat.h>
 #include <linux/kallsyms_compat.h>
 #include <linux/mutex_compat.h>
+#include <linux/module_compat.h>
 
 #ifndef HAVE_UINTPTR_T
 typedef unsigned long			uintptr_t;
diff --git a/include/sys/vnode.h b/include/sys/vnode.h
index 7972f6548..d8a8df272 100644
--- a/include/sys/vnode.h
+++ b/include/sys/vnode.h
@@ -215,6 +215,7 @@ extern int vn_getattr(vnode_t *vp, vattr_t *vap, int flags, void *x3, void *x4);
 extern int vn_fsync(vnode_t *vp, int flags, void *x3, void *x4);
 extern file_t *vn_getf(int fd);
 extern void vn_releasef(int fd);
+extern int vn_set_pwd(const char *filename);
 
 int vn_init(void);
 void vn_fini(void);
@@ -241,7 +242,7 @@ vn_putpage(vnode_t *vp, offset_t off, ssize_t size,
 #define getf					vn_getf
 #define releasef				vn_releasef
 
-extern void *rootdir;
+extern vnode_t *rootdir;
 
 #ifdef  __cplusplus
 }
diff --git a/module/spl/spl-generic.c b/module/spl/spl-generic.c
index 8bf97e0cf..dc0ac21d0 100644
--- a/module/spl/spl-generic.c
+++ b/module/spl/spl-generic.c
@@ -358,7 +358,8 @@ set_kallsyms_lookup_name(void)
 }
 #endif
 
-static int __init spl_init(void)
+static int
+__init spl_init(void)
 {
 	int rc = 0;
 
@@ -421,7 +422,8 @@ out1:
 	return rc;
 }
 
-static void spl_fini(void)
+static void
+spl_fini(void)
 {
 	ENTRY;
 
@@ -436,6 +438,26 @@ static void spl_fini(void)
 	debug_fini();
 }
 
+/* Called when a dependent module is loaded */
+void
+spl_setup(void)
+{
+        /*
+         * At module load time the pwd is set to '/' on a Solaris system.
+         * On a Linux system will be set to whatever directory the caller
+         * was in when executing insmod/modprobe.
+         */
+        vn_set_pwd("/");
+}
+EXPORT_SYMBOL(spl_setup);
+
+/* Called when a dependent module is unloaded */
+void
+spl_cleanup(void)
+{
+}
+EXPORT_SYMBOL(spl_cleanup);
+
 module_init(spl_init);
 module_exit(spl_fini);
 
diff --git a/module/spl/spl-vnode.c b/module/spl/spl-vnode.c
index 08c339a5a..7d2080022 100644
--- a/module/spl/spl-vnode.c
+++ b/module/spl/spl-vnode.c
@@ -34,7 +34,7 @@
 
 #define DEBUG_SUBSYSTEM S_VNODE
 
-void *rootdir = NULL;
+vnode_t *rootdir = (vnode_t *)0xabcd1234;
 EXPORT_SYMBOL(rootdir);
 
 static spl_kmem_cache_t *vn_cache;
@@ -602,6 +602,90 @@ vn_releasef(int fd)
 } /* releasef() */
 EXPORT_SYMBOL(releasef);
 
+#ifndef HAVE_SET_FS_PWD
+# ifdef HAVE_2ARGS_SET_FS_PWD
+/* Used from 2.6.25 - 2.6.31+ */
+void
+set_fs_pwd(struct fs_struct *fs, struct path *path)
+{
+        struct path old_pwd;
+
+        write_lock(&fs->lock);
+        old_pwd = fs->pwd;
+        fs->pwd = *path;
+        path_get(path);
+        write_unlock(&fs->lock);
+
+        if (old_pwd.dentry)
+                path_put(&old_pwd);
+}
+# else
+/* Used from 2.6.11 - 2.6.24 */
+void
+set_fs_pwd(struct fs_struct *fs, struct vfsmount *mnt, struct dentry *dentry)
+{
+        struct dentry *old_pwd;
+        struct vfsmount *old_pwdmnt;
+
+        write_lock(&fs->lock);
+        old_pwd = fs->pwd;
+        old_pwdmnt = fs->pwdmnt;
+        fs->pwdmnt = mntget(mnt);
+        fs->pwd = dget(dentry);
+        write_unlock(&fs->lock);
+
+        if (old_pwd) {
+                dput(old_pwd);
+                mntput(old_pwdmnt);
+        }
+}
+# endif /* HAVE_2ARGS_SET_FS_PWD */
+#endif /* HAVE_SET_FS_PWD */
+
+int
+vn_set_pwd(const char *filename)
+{
+#ifdef HAVE_2ARGS_SET_FS_PWD
+        struct path path;
+        int rc;
+        ENTRY;
+
+        rc = user_path_dir(filename, &path);
+        if (rc)
+                GOTO(out, rc);
+
+        rc = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_ACCESS);
+        if (rc)
+                GOTO(dput_and_out, rc);
+
+        set_fs_pwd(current->fs, &path);
+
+dput_and_out:
+        path_put(&path);
+#else
+        struct nameidata nd;
+        int rc;
+        ENTRY;
+
+        rc = __user_walk(filename,
+                         LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_CHDIR, &nd);
+        if (rc)
+                GOTO(out, rc);
+
+        rc = vfs_permission(&nd, MAY_EXEC);
+        if (rc)
+                GOTO(dput_and_out, rc);
+
+        set_fs_pwd(current->fs, nd.nd_mnt, nd.nd_dentry);
+
+dput_and_out:
+        vn_path_release(&nd);
+#endif /* HAVE_2ARGS_SET_FS_PWD */
+out:
+        RETURN(-rc);
+} /* vn_set_pwd() */
+EXPORT_SYMBOL(vn_set_pwd);
+
 static int
 vn_cache_constructor(void *buf, void *cdrarg, int kmflags)
 {
diff --git a/module/splat/splat-ctl.c b/module/splat/splat-ctl.c
index 159103980..9e52ab4fb 100644
--- a/module/splat/splat-ctl.c
+++ b/module/splat/splat-ctl.c
@@ -608,7 +608,7 @@ static struct cdev splat_cdev = {
 	.kobj   =	{ .name = SPLAT_NAME, },
 };
 
-static int __init
+static int
 splat_init(void)
 {
 	dev_t dev;
@@ -667,7 +667,7 @@ error:
 	return rc;
 }
 
-static void
+static int
 splat_fini(void)
 {
 	dev_t dev = MKDEV(SPLAT_MAJOR, 0);
@@ -695,10 +695,12 @@ splat_fini(void)
 	ASSERT(list_empty(&splat_module_list));
 	printk(KERN_INFO "SPLAT: Unloaded Solaris Porting LAyer "
 	       "Tests v%s\n", SPL_META_VERSION);
+
+	return 0;
 }
 
-module_init(splat_init);
-module_exit(splat_fini);
+spl_module_init(splat_init);
+spl_module_exit(splat_fini);
 
 MODULE_AUTHOR("Lawrence Livermore National Labs");
 MODULE_DESCRIPTION("Solaris Porting LAyer Tests");
diff --git a/spl_config.h.in b/spl_config.h.in
index bd42119cb..176da466b 100644
--- a/spl_config.h.in
+++ b/spl_config.h.in
@@ -12,6 +12,9 @@
 /* register_sysctl_table() wants 2 args */
 #undef HAVE_2ARGS_REGISTER_SYSCTL
 
+/* set_fs_pwd() wants 2 args */
+#undef HAVE_2ARGS_SET_FS_PWD
+
 /* vfs_unlink() wants 2 args */
 #undef HAVE_2ARGS_VFS_UNLINK
 
@@ -120,6 +123,9 @@
 /* __put_task_struct() is available */
 #undef HAVE_PUT_TASK_STRUCT
 
+/* set_fs_pwd() is available */
+#undef HAVE_SET_FS_PWD
+
 /* set_normalized_timespec() is available as export */
 #undef HAVE_SET_NORMALIZED_TIMESPEC_EXPORT