[PATCH] Rewrite proc seq operations via seq_list_xxx ones

[Pavel Emelyanov <xemul@openvz.org>]

Some time ago I posted a set of patches that consolidated
the seq files, walking the list_head-s. This set was merged
in the mm tree. /proc/diskstats and /proc/partitions files 
were included in this set, but a bit later this part was 
dropped because of conflicts with some other changes.

Here's the fixed version against the latest git block repo.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>

---

diff --git a/block/genhd.c b/block/genhd.c
index 3af1e7a..27f7061 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -264,39 +264,34 @@ void __init printk_all_partitions(void)
 
 #ifdef CONFIG_PROC_FS
 /* iterator */
-static void *part_start(struct seq_file *part, loff_t *pos)
+static void *disk_start(struct seq_file *part, loff_t *pos)
 {
-	struct list_head *p;
-	loff_t l = *pos;
-
 	mutex_lock(&block_subsys_lock);
-	list_for_each(p, &block_subsys.list)
-		if (!l--)
-			return list_entry(p, struct gendisk, kobj.entry);
-	return NULL;
+	return seq_list_start_head(&block_subsys.list, *pos);
 }
 
-static void *part_next(struct seq_file *part, void *v, loff_t *pos)
+static void *disk_next(struct seq_file *part, void *v, loff_t *pos)
 {
-	struct list_head *p = ((struct gendisk *)v)->kobj.entry.next;
-	++*pos;
-	return p==&block_subsys.list ? NULL :
-		list_entry(p, struct gendisk, kobj.entry);
+	return seq_list_next(v, &block_subsys.list, pos);
 }
 
-static void part_stop(struct seq_file *part, void *v)
+static void disk_stop(struct seq_file *part, void *v)
 {
 	mutex_unlock(&block_subsys_lock);
 }
 
 static int show_partition(struct seq_file *part, void *v)
 {
-	struct gendisk *sgp = v;
+	struct gendisk *sgp;
 	int n;
 	char buf[BDEVNAME_SIZE];
 
-	if (&sgp->kobj.entry == block_subsys.list.next)
+	if (v == &block_subsys.list) {
 		seq_puts(part, "major minor  #blocks  name\n\n");
+		return 0;
+	}
+
+	sgp = list_entry(v, struct gendisk, kobj.entry);
 
 	/* Don't show non-partitionable removeable devices or empty devices */
 	if (!get_capacity(sgp) ||
@@ -325,9 +320,9 @@ static int show_partition(struct seq_fil
 }
 
 struct seq_operations partitions_op = {
-	.start =part_start,
-	.next =	part_next,
-	.stop =	part_stop,
+	.start =disk_start,
+	.next =	disk_next,
+	.stop =	disk_stop,
 	.show =	show_partition
 };
 #endif
@@ -616,44 +611,22 @@ decl_subsys(block, &ktype_block, &block_
  */
 
 /* iterator */
-static void *diskstats_start(struct seq_file *part, loff_t *pos)
-{
-	loff_t k = *pos;
-	struct list_head *p;
-
-	mutex_lock(&block_subsys_lock);
-	list_for_each(p, &block_subsys.list)
-		if (!k--)
-			return list_entry(p, struct gendisk, kobj.entry);
-	return NULL;
-}
-
-static void *diskstats_next(struct seq_file *part, void *v, loff_t *pos)
-{
-	struct list_head *p = ((struct gendisk *)v)->kobj.entry.next;
-	++*pos;
-	return p==&block_subsys.list ? NULL :
-		list_entry(p, struct gendisk, kobj.entry);
-}
-
-static void diskstats_stop(struct seq_file *part, void *v)
-{
-	mutex_unlock(&block_subsys_lock);
-}
-
 static int diskstats_show(struct seq_file *s, void *v)
 {
-	struct gendisk *gp = v;
+	struct gendisk *gp;
 	char buf[BDEVNAME_SIZE];
 	int n = 0;
 
+	if (v == &block_subsys.list)
 	/*
-	if (&sgp->kobj.entry == block_subsys.kset.list.next)
 		seq_puts(s,	"major minor name"
 				"     rio rmerge rsect ruse wio wmerge "
 				"wsect wuse running use aveq"
 				"\n\n");
 	*/
+		return 0;
+
+	gp = list_entry(v, struct gendisk, kobj.entry);
  
 	preempt_disable();
 	disk_round_stats(gp);
@@ -686,9 +659,9 @@ static int diskstats_show(struct seq_fil
 }
 
 struct seq_operations diskstats_op = {
-	.start	= diskstats_start,
-	.next	= diskstats_next,
-	.stop	= diskstats_stop,
+	.start	= disk_start,
+	.next	= disk_next,
+	.stop	= disk_stop,
 	.show	= diskstats_show
 };