xfs: pass xfsstats structures to handlers and macros

This patch is the next step toward per-fs xfs stats. The patch makes
the show and clear routines able to handle any stats structure
associated with a kobject.

Instead of a single global xfsstats structure, add kobject and a pointer
to a per-cpu struct xfsstats. Modify the macros that manipulate the stats
accordingly: XFS_STATS_INC, XFS_STATS_DEC, and XFS_STATS_ADD now access
xfsstats->xs_stats.

The sysfs functions need to get from the kobject back to the xfsstats
structure which contains it, and pass the pointer to the ->xs_stats
percpu structure into the show & clear routines.

Signed-off-by: Bill O'Donnell <billodo@redhat.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/xfs/xfs_stats.h b/fs/xfs/xfs_stats.h
index 18807b5..54f2260 100644
--- a/fs/xfs/xfs_stats.h
+++ b/fs/xfs/xfs_stats.h
@@ -18,9 +18,6 @@
 #ifndef __XFS_STATS_H__
 #define __XFS_STATS_H__
 
-int xfs_stats_format(char *buf);
-void xfs_stats_clearall(void);
-
 #if defined(CONFIG_PROC_FS) && !defined(XFS_STATS_OFF)
 
 #include <linux/percpu.h>
@@ -217,15 +214,18 @@
 	__uint64_t		xs_read_bytes;
 };
 
-DECLARE_PER_CPU(struct xfsstats, xfsstats);
+int xfs_stats_format(struct xfsstats __percpu *stats, char *buf);
+void xfs_stats_clearall(struct xfsstats __percpu *stats);
+extern struct xstats xfsstats;
 
-/*
- * We don't disable preempt, not too worried about poking the
- * wrong CPU's stat for now (also aggregated before reporting).
- */
-#define XFS_STATS_INC(v)	(per_cpu(xfsstats, current_cpu()).v++)
-#define XFS_STATS_DEC(v)	(per_cpu(xfsstats, current_cpu()).v--)
-#define XFS_STATS_ADD(v, inc)	(per_cpu(xfsstats, current_cpu()).v += (inc))
+#define XFS_STATS_INC(v)	\
+	(per_cpu_ptr(xfsstats.xs_stats, current_cpu())->v++)
+
+#define XFS_STATS_DEC(v)	\
+	(per_cpu_ptr(xfsstats.xs_stats, current_cpu())->v--)
+
+#define XFS_STATS_ADD(v, inc)	\
+	(per_cpu_ptr(xfsstats.xs_stats, current_cpu())->v += (inc))
 
 extern int xfs_init_procfs(void);
 extern void xfs_cleanup_procfs(void);