Update vn_set_pwd() to allow user|kernal address for filename

During module init spl_setup()->The vn_set_pwd("/") was failing
with -EFAULT because user_path_dir() and __user_walk() both
expect 'filename' to be a user space address and it's not in
this case.  To handle this the data segment size is increased
to to ensure strncpy_from_user() does not fail with -EFAULT.

Additionally, I've added a printk() warning to catch this and
log it to the console if it ever reoccurs.  I thought everything
was working properly here because there consequences of this
failing are subtle and usually non-critical.

1 files changed, 5 insertions, 1 deletions

diff --git a/module/spl/spl-generic.c b/module/spl/spl-generic.c
index 290c5275d..aaf1a4c10 100644
--- a/module/spl/spl-generic.c
+++ b/module/spl/spl-generic.c
@@ -444,12 +444,16 @@ spl_fini(void)
 void
 spl_setup(void)
 {
+        int rc;
+
         /*
          * 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("/");
+        rc = vn_set_pwd("/");
+        if (rc)
+                printk("SPL: Warning unable to set pwd to '/': %d\n", rc);
 }
 EXPORT_SYMBOL(spl_setup);