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>

fs/xfs/xfs_linux.h

@@ -171,6 +171,13 @@ struct xfs_kobj {
 	struct completion	complete;
 };
 
+struct xstats {
+	struct xfsstats __percpu	*xs_stats;
+	struct xfs_kobj			xs_kobj;
+};
+
+extern struct xstats xfsstats;
+
 /* Kernel uid/gid conversion. These are used to convert to/from the on disk
  * uid_t/gid_t types to the kuid_t/kgid_t types that the kernel uses internally.
  * The conversion here is type only, the value will remain the same since we

fs/xfs/xfs_stats.c

@@ -18,18 +18,18 @@
 #include "xfs.h"
 #include <linux/proc_fs.h>
 
-DEFINE_PER_CPU(struct xfsstats, xfsstats);
+struct xstats xfsstats;
 
-static int counter_val(int idx)
+static int counter_val(struct xfsstats __percpu *stats, int idx)
 {
 	int val = 0, cpu;
 
 	for_each_possible_cpu(cpu)
-		val += *(((__u32 *)&per_cpu(xfsstats, cpu) + idx));
+		val += *(((__u32 *)per_cpu_ptr(stats, cpu) + idx));
 	return val;
 }
 
-int xfs_stats_format(char *buf)
+int xfs_stats_format(struct xfsstats __percpu *stats, char *buf)
 {
 	int		i, j;
 	int		len = 0;
@@ -73,14 +73,14 @@ int xfs_stats_format(char *buf)
 		/* inner loop does each group */
 		for (; j < xstats[i].endpoint; j++)
 			len += snprintf(buf + len, PATH_MAX - len, " %u",
-					counter_val(j));
+					counter_val(stats, 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;
+		xs_xstrat_bytes += per_cpu_ptr(stats, i)->xs_xstrat_bytes;
+		xs_write_bytes += per_cpu_ptr(stats, i)->xs_write_bytes;
+		xs_read_bytes += per_cpu_ptr(stats, i)->xs_read_bytes;
 	}
 
 	len += snprintf(buf + len, PATH_MAX-len, "xpc %Lu %Lu %Lu\n",
@@ -95,7 +95,7 @@ int xfs_stats_format(char *buf)
 	return len;
 }
 
-void xfs_stats_clearall(void)
+void xfs_stats_clearall(struct xfsstats __percpu *stats)
 {
 	int		c;
 	__uint32_t	vn_active;
@@ -104,9 +104,9 @@ void xfs_stats_clearall(void)
 	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;
+		vn_active = per_cpu_ptr(stats, c)->vn_active;
+		memset(per_cpu_ptr(stats, c), 0, sizeof(*stats));
+		per_cpu_ptr(stats, c)->vn_active = vn_active;
 		preempt_enable();
 	}
 }
@@ -117,10 +117,8 @@ static int xqm_proc_show(struct seq_file *m, void *v)
 {
 	/* maximum; incore; ratio free to inuse; freelist */
 	seq_printf(m, "%d\t%d\t%d\t%u\n",
-			0,
-			counter_val(XFSSTAT_END_XQMSTAT),
-			0,
-			counter_val(XFSSTAT_END_XQMSTAT + 1));
+		   0, counter_val(xfsstats.xs_stats, XFSSTAT_END_XQMSTAT),
+		   0, counter_val(xfsstats.xs_stats, XFSSTAT_END_XQMSTAT + 1));
 	return 0;
 }
 
@@ -144,7 +142,7 @@ static int xqmstat_proc_show(struct seq_file *m, void *v)
 
 	seq_printf(m, "qm");
 	for (j = XFSSTAT_END_IBT_V2; j < XFSSTAT_END_XQMSTAT; j++)
-		seq_printf(m, " %u", counter_val(j));
+		seq_printf(m, " %u", counter_val(xfsstats.xs_stats, j));
 	seq_putc(m, '\n');
 	return 0;
 }

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 @@ struct xfsstats {
 	__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);

fs/xfs/xfs_super.c

@@ -61,7 +61,6 @@ static kmem_zone_t *xfs_ioend_zone;
 mempool_t *xfs_ioend_pool;
 
 static struct kset *xfs_kset;		/* top-level xfs sysfs dir */
-static struct xfs_kobj xfs_stats_kobj;	/* global stats sysfs attrs */
 #ifdef DEBUG
 static struct xfs_kobj xfs_dbg_kobj;	/* global debug sysfs attrs */
 #endif
@@ -1842,11 +1841,18 @@ init_xfs_fs(void)
 		goto out_sysctl_unregister;
 	}
 
-	xfs_stats_kobj.kobject.kset = xfs_kset;
-	error = xfs_sysfs_init(&xfs_stats_kobj, &xfs_stats_ktype, NULL,
+	xfsstats.xs_kobj.kobject.kset = xfs_kset;
+
+	xfsstats.xs_stats = alloc_percpu(struct xfsstats);
+	if (!xfsstats.xs_stats) {
+		error = -ENOMEM;
+		goto out_kset_unregister;
+	}
+
+	error = xfs_sysfs_init(&xfsstats.xs_kobj, &xfs_stats_ktype, NULL,
 			       "stats");
 	if (error)
-		goto out_kset_unregister;
+		goto out_free_stats;
 
 #ifdef DEBUG
 	xfs_dbg_kobj.kobject.kset = xfs_kset;
@@ -1871,7 +1877,9 @@ init_xfs_fs(void)
 	xfs_sysfs_del(&xfs_dbg_kobj);
  out_remove_stats_kobj:
 #endif
-	xfs_sysfs_del(&xfs_stats_kobj);
+	xfs_sysfs_del(&xfsstats.xs_kobj);
+ out_free_stats:
+	free_percpu(xfsstats.xs_stats);
  out_kset_unregister:
 	kset_unregister(xfs_kset);
  out_sysctl_unregister:
@@ -1898,7 +1906,8 @@ exit_xfs_fs(void)
 #ifdef DEBUG
 	xfs_sysfs_del(&xfs_dbg_kobj);
 #endif
-	xfs_sysfs_del(&xfs_stats_kobj);
+	xfs_sysfs_del(&xfsstats.xs_kobj);
+	free_percpu(xfsstats.xs_stats);
 	kset_unregister(xfs_kset);
 	xfs_sysctl_unregister();
 	xfs_cleanup_procfs();

fs/xfs/xfs_sysctl.c

@@ -37,7 +37,7 @@ xfs_stats_clear_proc_handler(
 	ret = proc_dointvec_minmax(ctl, write, buffer, lenp, ppos);
 
 	if (!ret && write && *valp) {
-		xfs_stats_clearall();
+		xfs_stats_clearall(xfsstats.xs_stats);
 		xfs_stats_clear = 0;
 	}
 

fs/xfs/xfs_sysfs.c

@@ -131,12 +131,22 @@ struct kobj_type xfs_dbg_ktype = {
 
 /* stats */
 
+static inline struct xstats *
+to_xstats(struct kobject *kobject)
+{
+	struct xfs_kobj *kobj = to_kobj(kobject);
+
+	return container_of(kobj, struct xstats, xs_kobj);
+}
+
 STATIC ssize_t
 stats_show(
 	struct kobject	*kobject,
 	char		*buf)
 {
-	return xfs_stats_format(buf);
+	struct xstats	*stats = to_xstats(kobject);
+
+	return xfs_stats_format(stats->xs_stats, buf);
 }
 XFS_SYSFS_ATTR_RO(stats);
 
@@ -148,6 +158,7 @@ stats_clear_store(
 {
 	int		ret;
 	int		val;
+	struct xstats	*stats = to_xstats(kobject);
 
 	ret = kstrtoint(buf, 0, &val);
 	if (ret)
@@ -155,7 +166,8 @@ stats_clear_store(
 
 	if (val != 1)
 		return -EINVAL;
-	xfs_stats_clearall();
+
+	xfs_stats_clearall(stats->xs_stats);
 	return count;
 }
 XFS_SYSFS_ATTR_WO(stats_clear);