ubi: Fix seq_file usage in detailed_erase_block_info debugfs file

[ Upstream commit 0e7572c ]

3bfa7e1 ("fs/seq_file.c: seq_read(): add info message about buggy .next functions")
showed that we don't use seq_file correctly.
So make sure that our ->next function always updates the position.

Fixes: 7bccd12 ("ubi: Add debugfs file for tracking PEB state")
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/mtd/ubi/debug.c

@@ -392,9 +392,6 @@ static void *eraseblk_count_seq_start(struct seq_file *s, loff_t *pos)
 {
 	struct ubi_device *ubi = s->private;
 
-	if (*pos == 0)
-		return SEQ_START_TOKEN;
-
 	if (*pos < ubi->peb_count)
 		return pos;
 
@@ -408,8 +405,6 @@ static void *eraseblk_count_seq_next(struct seq_file *s, void *v, loff_t *pos)
 {
 	struct ubi_device *ubi = s->private;
 
-	if (v == SEQ_START_TOKEN)
-		return pos;
 	(*pos)++;
 
 	if (*pos < ubi->peb_count)
@@ -431,11 +426,8 @@ static int eraseblk_count_seq_show(struct seq_file *s, void *iter)
 	int err;
 
 	/* If this is the start, print a header */
-	if (iter == SEQ_START_TOKEN) {
-		seq_puts(s,
-			 "physical_block_number\terase_count\tblock_status\tread_status\n");
-		return 0;
-	}
+	if (*block_number == 0)
+		seq_puts(s, "physical_block_number\terase_count\n");
 
 	err = ubi_io_is_bad(ubi, *block_number);
 	if (err)