CRED: Wrap task credential accesses in the XFS filesystem

Wrap access to task credentials so that they can be separated more easily from
the task_struct during the introduction of COW creds.

Change most current->(|e|s|fs)[ug]id to current_(|e|s|fs)[ug]id().

Change some task->e?[ug]id to task_e?[ug]id().  In some places it makes more
sense to use RCU directly rather than a convenient wrapper; these will be
addressed by later patches.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
diff --git a/fs/xfs/linux-2.6/xfs_cred.h b/fs/xfs/linux-2.6/xfs_cred.h
index 98da219..e279d00 100644
--- a/fs/xfs/linux-2.6/xfs_cred.h
+++ b/fs/xfs/linux-2.6/xfs_cred.h
@@ -24,7 +24,7 @@
  * Credentials
  */
 typedef struct cred {
-	/* EMPTY */
+       /* EMPTY */
 } cred_t;
 
 #endif  /* __XFS_CRED_H__ */
diff --git a/fs/xfs/linux-2.6/xfs_ioctl.c b/fs/xfs/linux-2.6/xfs_ioctl.c
index d25694e..f1bd6c3 100644
--- a/fs/xfs/linux-2.6/xfs_ioctl.c
+++ b/fs/xfs/linux-2.6/xfs_ioctl.c
@@ -1006,7 +1006,7 @@
 	 * to the file owner ID, except in cases where the
 	 * CAP_FSETID capability is applicable.
 	 */
-	if (current->fsuid != ip->i_d.di_uid && !capable(CAP_FOWNER)) {
+	if (current_fsuid() != ip->i_d.di_uid && !capable(CAP_FOWNER)) {
 		code = XFS_ERROR(EPERM);
 		goto error_return;
 	}