About raid5 read error handle when raid5 was degraded.

 Hi all:
	I readed the latest code in function :

raid5_end_read_request():

quoted

else if (conf->mddev->degraded >= conf->max_degraded)
		printk_ratelimited(
			KERN_WARNING
			"md/raid:%s: read error not correctable "
			"(sector %llu on %s).\n",
			mdname(conf->mddev),
			(unsigned long long)(sh->sector
					     + rdev->data_offset),
			bdn);

If this occur,then exec md_error().In md_error(), remove this disk.
The raid5 will fail and lost all data.
Why do call rdev_set_badsector() for this situation?

														Thanks!

 				
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majianpeng
2012-05-21