[JFFS2] add write verify on dataflash.

Add the write verification buffer to the dataflash.  The mtd_dataflash has
the CONFIG_DATAFLASH_WRITE_VERIFY so is better a change to Kconfig.
Signed-off-by: Michael Trimarchi <trimarchimichael@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>

fs/jffs2/wbuf.c

@@ -1236,12 +1236,24 @@ int jffs2_dataflash_setup(struct jffs2_sb_info *c) {
 	if (!c->wbuf)
 		return -ENOMEM;
 
+#ifdef CONFIG_JFFS2_FS_WBUF_VERIFY
+	c->wbuf_verify = kmalloc(c->wbuf_pagesize, GFP_KERNEL);
+	if (!c->wbuf_verify) {
+		kfree(c->oobbuf);
+		kfree(c->wbuf);
+		return -ENOMEM;
+	}
+#endif
+
 	printk(KERN_INFO "JFFS2 write-buffering enabled buffer (%d) erasesize (%d)\n", c->wbuf_pagesize, c->sector_size);
 
 	return 0;
 }
 
 void jffs2_dataflash_cleanup(struct jffs2_sb_info *c) {
+#ifdef CONFIG_JFFS2_FS_WBUF_VERIFY
+	kfree(c->wbuf_verify);
+#endif
 	kfree(c->wbuf);
 }