xfs: create global stats and stats_clear in sysfs

Currently, xfs global stats are in procfs. This patch introduces
(replicates) the global stats in sysfs. Additionally a stats_clear file
is introduced in sysfs.

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.c b/fs/xfs/xfs_stats.c
index f224038..e19b84a 100644
--- a/fs/xfs/xfs_stats.c
+++ b/fs/xfs/xfs_stats.c
@@ -29,6 +29,88 @@
 	return val;
 }
 
+int xfs_stats_format(char *buf)
+{
+	int		i, j;
+	int		len = 0;
+	__uint64_t	xs_xstrat_bytes = 0;
+	__uint64_t	xs_write_bytes = 0;
+	__uint64_t	xs_read_bytes = 0;
+
+	static const struct xstats_entry {
+		char	*desc;
+		int	endpoint;
+	} xstats[] = {
+		{ "extent_alloc",	XFSSTAT_END_EXTENT_ALLOC	},
+		{ "abt",		XFSSTAT_END_ALLOC_BTREE		},
+		{ "blk_map",		XFSSTAT_END_BLOCK_MAPPING	},
+		{ "bmbt",		XFSSTAT_END_BLOCK_MAP_BTREE	},
+		{ "dir",		XFSSTAT_END_DIRECTORY_OPS	},
+		{ "trans",		XFSSTAT_END_TRANSACTIONS	},
+		{ "ig",			XFSSTAT_END_INODE_OPS		},
+		{ "log",		XFSSTAT_END_LOG_OPS		},
+		{ "push_ail",		XFSSTAT_END_TAIL_PUSHING	},
+		{ "xstrat",		XFSSTAT_END_WRITE_CONVERT	},
+		{ "rw",			XFSSTAT_END_READ_WRITE_OPS	},
+		{ "attr",		XFSSTAT_END_ATTRIBUTE_OPS	},
+		{ "icluster",		XFSSTAT_END_INODE_CLUSTER	},
+		{ "vnodes",		XFSSTAT_END_VNODE_OPS		},
+		{ "buf",		XFSSTAT_END_BUF			},
+		{ "abtb2",		XFSSTAT_END_ABTB_V2		},
+		{ "abtc2",		XFSSTAT_END_ABTC_V2		},
+		{ "bmbt2",		XFSSTAT_END_BMBT_V2		},
+		{ "ibt2",		XFSSTAT_END_IBT_V2		},
+		{ "fibt2",		XFSSTAT_END_FIBT_V2		},
+		/* we print both series of quota information together */
+		{ "qm",			XFSSTAT_END_QM			},
+	};
+
+	/* Loop over all stats groups */
+
+	for (i = j = 0; i < ARRAY_SIZE(xstats); i++) {
+		len += snprintf(buf + len, PATH_MAX - len, "%s",
+				xstats[i].desc);
+		/* inner loop does each group */
+		for (; j < xstats[i].endpoint; j++)
+			len += snprintf(buf + len, PATH_MAX - len, " %u",
+					counter_val(j));
+		len += snprintf(buf + len, PATH_MAX - len, "\n");
+	}
+	/* extra precision counters */
+	for_each_possible_cpu(i) {
+		xs_xstrat_bytes += per_cpu(xfsstats, i).xs_xstrat_bytes;
+		xs_write_bytes += per_cpu(xfsstats, i).xs_write_bytes;
+		xs_read_bytes += per_cpu(xfsstats, i).xs_read_bytes;
+	}
+
+	len += snprintf(buf + len, PATH_MAX-len, "xpc %Lu %Lu %Lu\n",
+			xs_xstrat_bytes, xs_write_bytes, xs_read_bytes);
+	len += snprintf(buf + len, PATH_MAX-len, "debug %u\n",
+#if defined(DEBUG)
+		1);
+#else
+		0);
+#endif
+
+	return len;
+}
+
+void xfs_stats_clearall(void)
+{
+	int		c;
+	__uint32_t	vn_active;
+
+	xfs_notice(NULL, "Clearing xfsstats");
+	for_each_possible_cpu(c) {
+		preempt_disable();
+		/* save vn_active, it's a universal truth! */
+		vn_active = per_cpu(xfsstats, c).vn_active;
+		memset(&per_cpu(xfsstats, c), 0, sizeof(struct xfsstats));
+		per_cpu(xfsstats, c).vn_active = vn_active;
+		preempt_enable();
+	}
+}
+
 static int xfs_stat_proc_show(struct seq_file *m, void *v)
 {
 	int		i, j;