mm, vmalloc: move get_vmalloc_info() to vmalloc.c

Now get_vmalloc_info() is in fs/proc/mmu.c.  There is no reason that this
code must be here and it's implementation needs vmlist_lock and it iterate
a vmlist which may be internal data structure for vmalloc.

It is preferable that vmlist_lock and vmlist is only used in vmalloc.c
for maintainability. So move the code to vmalloc.c

Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Dave Anderson <anderson@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 6071e91..698b1e5 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -158,4 +158,22 @@
 # endif
 #endif
 
+struct vmalloc_info {
+	unsigned long   used;
+	unsigned long   largest_chunk;
+};
+
+#ifdef CONFIG_MMU
+#define VMALLOC_TOTAL (VMALLOC_END - VMALLOC_START)
+extern void get_vmalloc_info(struct vmalloc_info *vmi);
+#else
+
+#define VMALLOC_TOTAL 0UL
+#define get_vmalloc_info(vmi)			\
+do {						\
+	(vmi)->used = 0;			\
+	(vmi)->largest_chunk = 0;		\
+} while (0)
+#endif
+
 #endif /* _LINUX_VMALLOC_H */