task_struct: make journal_info conditional

journal_info in task_struct is used in journaling file system only.  So
introduce CONFIG_FS_JOURNAL_INFO and make it conditional.

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: KONISHI Ryusuke <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 294eb2f..7d38849 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1446,8 +1446,10 @@
 	gfp_t lockdep_reclaim_gfp;
 #endif
 
+#ifdef CONFIG_FS_JOURNAL_INFO
 /* journalling filesystem info */
 	void *journal_info;
+#endif
 
 /* stacked block device info */
 	struct bio *bio_list, **bio_tail;