proc: switch /proc/cmdline to seq_file

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

fs/proc/Makefile

@@ -9,6 +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	+= cmdline.o
 proc-y	+= loadavg.o
 proc-y	+= meminfo.o
 proc-y	+= uptime.o

fs/proc/cmdline.c

+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+
+static int cmdline_proc_show(struct seq_file *m, void *v)
+{
+	seq_printf(m, "%s\n", saved_command_line);
+	return 0;
+}
+
+static int cmdline_proc_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, cmdline_proc_show, NULL);
+}
+
+static const struct file_operations cmdline_proc_fops = {
+	.open		= cmdline_proc_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+static int __init proc_cmdline_init(void)
+{
+	proc_create("cmdline", 0, NULL, &cmdline_proc_fops);
+	return 0;
+}
+module_init(proc_cmdline_init);

fs/proc/proc_misc.c

@@ -472,15 +472,6 @@ static const struct file_operations proc_interrupts_operations = {
 	.release	= seq_release,
 };
 
-static int cmdline_read_proc(char *page, char **start, off_t off,
-				 int count, int *eof, void *data)
-{
-	int len;
-
-	len = sprintf(page, "%s\n", saved_command_line);
-	return proc_calc_metrics(page, start, off, count, eof, len);
-}
-
 #ifdef CONFIG_FILE_LOCKING
 static int locks_open(struct inode *inode, struct file *filp)
 {
@@ -641,7 +632,6 @@ void __init proc_misc_init(void)
 		char *name;
 		int (*read_proc)(char*,char**,off_t,int,int*,void*);
 	} *p, simple_ones[] = {
-		{"cmdline",	cmdline_read_proc},
 		{"execdomains",	execdomains_read_proc},
 		{NULL,}
 	};