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Date: Thu, 22 Sep 2005 18:14:10 +0200
From: Peter Menzebach <pm@mw-itcon.de>
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To: Andrew Victor <andrew@sanpeople.com>
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Cc: "Artem B. Bityutskiy" <dedekind@yandex.ru>, linux-mtd@lists.infradead.org
Subject: Re: data  loss on jffs2 filesystem on dataflash
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Andrew Victor wrote:

> This magic minimum block size could always be calculated in JFFS2 (in
> jffs2_dataflash_setup).  It is a JFFS2-specific value.
> Just calculate an 'N' where:
>    (N * mtd->erasesize) >= jffs2_minimum_block_size
> and
>    (mtd->size % (N * mtd->erasesize)) == 0

How about this in jffs2_dataflash_setup:

--- /arm/src/mtd/fs/jffs2/wbuf.c	2005-09-22 13:33:42.000000000 +0200
+++ wbuf.c	2005-09-22 17:52:17.000000000 +0200
@@ -1204,14 +1197,28 @@
  	
  	/* Initialize write buffer */
  	init_rwsem(&c->wbuf_sem);
-	c->wbuf_pagesize = c->sector_size;
+	c->wbuf_pagesize = c->mtd->erasesize;
+
+	c->sector_size = ((JFFS2_MIN_SECTOR_SIZE + c->mtd->erasesize - 1) /
+			  c->mtd->erasesize) * c->mtd->erasesize;
+
+	while ((5*c->sector_size < c->mtd->size) &&
+		((c->mtd->size % c->sector_size) != 0))
+	{
+		c->sector_size+=c->mtd->erasesize;
+	}
+	if ((c->mtd->size % c->sector_size) != 0) {
+		printk(KERN_WARNING "JFFS2 no suitable sector size found\n");
+		return (1);
+	};
+	
  	c->wbuf_ofs = 0xFFFFFFFF;

  	c->wbuf = kmalloc(c->wbuf_pagesize, GFP_KERNEL);
  	if (!c->wbuf)
  		return -ENOMEM;

-	printk(KERN_INFO "JFFS2 write-buffering enabled (%i)\n", 
c->wbuf_pagesize);
+	printk(KERN_INFO "JFFS2 write-buffering enabled (%i) erasesize 
(%i)\n", c->wbuf_pagesize, c->sector_size);

  	return 0;
  }


-- 
Peter Menzebach
Menzebach und Wolff IT-Consulting GbR
Phone +49 751 355 387 1