[ARM] mtd: Collect bad block count for ecc stats lazily.

Normally bad block counts for ECC stats are collected during boot time.
This can be done lazily when the ECCGETSTATS ioctl is invoked on the
partition. This can significantly decrease boot time, depending on the
size of the partition. Also rescanning on every ioctl invocation helps
in having the latest bad block count rather than depending on the count
that is collected during boot.

Signed-off-by: Murali Palnati <[email protected]>

Author: Murali Palnati

drivers/mtd/Kconfig

@@ -45,6 +45,18 @@ config MTD_PARTITIONS
 	  devices. Partitioning on NFTL 'devices' is a different - that's the
 	  'normal' form of partitioning used on a block device.
 
+config MTD_LAZYECCSTATS
+	bool "MTD Lazy ECC Stats collection support"
+	depends on MTD_PARTITIONS
+	default n
+	help
+	  Normally bad block counts for ECC stats are collected at boot time.
+	  This option delays the badblock stats collection until ECCGETSTATS
+	  ioctl is invoked on the partition.
+
+	  This can significantly decrease boot times depending on the size of
+	  the partition.  If unsure, say 'N'.
+
 config MTD_TESTS
 	tristate "MTD tests support"
 	depends on m

drivers/mtd/mtdchar.c

@@ -16,6 +16,7 @@
 
 #include <linux/mtd/mtd.h>
 #include <linux/mtd/compatmac.h>
+#include <linux/mtd/partitions.h>
 
 #include <asm/uaccess.h>
 
@@ -744,6 +745,9 @@ static int mtd_ioctl(struct inode *inode, struct file *file,
 
 	case ECCGETSTATS:
 	{
+#ifdef CONFIG_MTD_LAZYECCSTATS
+		part_fill_badblockstats(mtd);
+#endif
 		if (copy_to_user(argp, &mtd->ecc_stats,
 				 sizeof(struct mtd_ecc_stats)))
 			return -EFAULT;

drivers/mtd/mtdpart.c

@@ -294,6 +294,21 @@ static int part_block_markbad(struct mtd_info *mtd, loff_t ofs)
 	return res;
 }
 
+void part_fill_badblockstats(struct mtd_info *mtd)
+{
+	struct mtd_part *part = PART(mtd);
+	if (part->master->block_isbad) {
+		uint64_t offs = 0;
+		mtd->ecc_stats.badblocks = 0;
+		while (offs < mtd->size) {
+			if (part->master->block_isbad(part->master,
+						offs + part->offset))
+				mtd->ecc_stats.badblocks++;
+			offs += mtd->erasesize;
+		}
+	}
+}
+
 /*
  * This function unregisters and destroy all slave MTD objects which are
  * attached to the given master MTD object.
@@ -465,16 +480,10 @@ static struct mtd_part *add_one_partition(struct mtd_info *master,
 	}
 
 	slave->mtd.ecclayout = master->ecclayout;
-	if (master->block_isbad) {
-		uint64_t offs = 0;
 
-		while (offs < slave->mtd.size) {
-			if (master->block_isbad(master,
-						offs + slave->offset))
-				slave->mtd.ecc_stats.badblocks++;
-			offs += slave->mtd.erasesize;
-		}
-	}
+#ifndef CONFIG_MTD_LAZYECCSTATS
+	part_fill_badblockstats(&(slave->mtd));
+#endif
 
 out_register:
 	if (part->mtdp) {

include/linux/mtd/partitions.h

@@ -50,6 +50,7 @@ struct mtd_partition {
 
 int add_mtd_partitions(struct mtd_info *, const struct mtd_partition *, int);
 int del_mtd_partitions(struct mtd_info *);
+void part_fill_badblockstats(struct mtd_info *mtd);
 
 /*
  * Functions dealing with the various ways of partitioning the space