proc: switch /proc/loadavg to seq_file

and move it to fs/proc/loadavg.c while I'm at it.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>

fs/proc/Makefile

@@ -9,7 +9,7 @@ proc-$(CONFIG_MMU)	:= mmu.o task_mmu.o
 
 proc-y       += inode.o root.o base.o generic.o array.o \
 		proc_tty.o proc_misc.o
-
+proc-y	+= loadavg.o
 proc-$(CONFIG_PROC_SYSCTL)	+= proc_sysctl.o
 proc-$(CONFIG_NET)		+= proc_net.o
 proc-$(CONFIG_PROC_KCORE)	+= kcore.o

fs/proc/loadavg.c

+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/pid_namespace.h>
+#include <linux/proc_fs.h>
+#include <linux/sched.h>
+#include <linux/seq_file.h>
+#include <linux/seqlock.h>
+#include <linux/time.h>
+
+#define LOAD_INT(x) ((x) >> FSHIFT)
+#define LOAD_FRAC(x) LOAD_INT(((x) & (FIXED_1-1)) * 100)
+
+static int loadavg_proc_show(struct seq_file *m, void *v)
+{
+	int a, b, c;
+	unsigned long seq;
+
+	do {
+		seq = read_seqbegin(&xtime_lock);
+		a = avenrun[0] + (FIXED_1/200);
+		b = avenrun[1] + (FIXED_1/200);
+		c = avenrun[2] + (FIXED_1/200);
+	} while (read_seqretry(&xtime_lock, seq));
+
+	seq_printf(m, "%d.%02d %d.%02d %d.%02d %ld/%d %d\n",
+		LOAD_INT(a), LOAD_FRAC(a),
+		LOAD_INT(b), LOAD_FRAC(b),
+		LOAD_INT(c), LOAD_FRAC(c),
+		nr_running(), nr_threads,
+		task_active_pid_ns(current)->last_pid);
+	return 0;
+}
+
+static int loadavg_proc_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, loadavg_proc_show, NULL);
+}
+
+static const struct file_operations loadavg_proc_fops = {
+	.open		= loadavg_proc_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+static int __init proc_loadavg_init(void)
+{
+	proc_create("loadavg", 0, NULL, &loadavg_proc_fops);
+	return 0;
+}
+module_init(proc_loadavg_init);

fs/proc/proc_misc.c

@@ -57,8 +57,6 @@
 #include <asm/div64.h>
 #include "internal.h"
 
-#define LOAD_INT(x) ((x) >> FSHIFT)
-#define LOAD_FRAC(x) LOAD_INT(((x) & (FIXED_1-1)) * 100)
 /*
  * Warning: stuff below (imported functions) assumes that its output will fit
  * into one page. For some of those functions it may be wrong. Moreover, we
@@ -80,29 +78,6 @@ static int proc_calc_metrics(char *page, char **start, off_t off,
 	return len;
 }
 
-static int loadavg_read_proc(char *page, char **start, off_t off,
-				 int count, int *eof, void *data)
-{
-	int a, b, c;
-	int len;
-	unsigned long seq;
-
-	do {
-		seq = read_seqbegin(&xtime_lock);
-		a = avenrun[0] + (FIXED_1/200);
-		b = avenrun[1] + (FIXED_1/200);
-		c = avenrun[2] + (FIXED_1/200);
-	} while (read_seqretry(&xtime_lock, seq));
-
-	len = sprintf(page,"%d.%02d %d.%02d %d.%02d %ld/%d %d\n",
-		LOAD_INT(a), LOAD_FRAC(a),
-		LOAD_INT(b), LOAD_FRAC(b),
-		LOAD_INT(c), LOAD_FRAC(c),
-		nr_running(), nr_threads,
-		task_active_pid_ns(current)->last_pid);
-	return proc_calc_metrics(page, start, off, count, eof, len);
-}
-
 static int uptime_read_proc(char *page, char **start, off_t off,
 				 int count, int *eof, void *data)
 {
@@ -861,7 +836,6 @@ void __init proc_misc_init(void)
 		char *name;
 		int (*read_proc)(char*,char**,off_t,int,int*,void*);
 	} *p, simple_ones[] = {
-		{"loadavg",     loadavg_read_proc},
 		{"uptime",	uptime_read_proc},
 		{"meminfo",	meminfo_read_proc},
 		{"version",	version_read_proc},