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From: Neil Brown <neilb@cse.unsw.edu.au>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Date: Mon, 27 Nov 2000 14:41:53 +1100 (EST)
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cc: linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] (test11-ac4)  unbelievably silly (fatal) typo in raid5.c
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Alan,
 raid5 rebuild has been fatally flawed ever since it got into 2.4, and
 my recent testing has been looking at speed more than correctness, so
 I didn't notice until now.

 raid5_sync_request is handed a block number in 1K units and needs to 
 convert to 512byte sector units.
 I could have used   (block_nr*2)
 I could have used   (block_nr<<1)
 but instead I used  (block_nr<<2)  !!!!  :-(

Please apply the following patch.

Thanks, 
NeilBrown

--- ./drivers/md/raid5.c	2000/11/27 02:46:45	1.1
+++ ./drivers/md/raid5.c	2000/11/27 02:47:37	1.2
@@ -1516,8 +1516,8 @@
 	raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
 	struct stripe_head *sh;
 	int sectors_per_chunk = conf->chunk_size >> 9;
-	unsigned long stripe = (block_nr<<2)/sectors_per_chunk;
-	int chunk_offset = (block_nr<<2) % sectors_per_chunk;
+	unsigned long stripe = (block_nr<<1)/sectors_per_chunk;
+	int chunk_offset = (block_nr<<1) % sectors_per_chunk;
 	int dd_idx, pd_idx;
 	unsigned long first_sector;
 	int raid_disks = conf->raid_disks;
-
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