[PATCH] md: better handling of readerrors with raid5.
This patch changes the behaviour of raid5 when it gets a read error.
Instead of just failing the device, it tried to find out what should have
been there, and writes it over the bad block. For some media-errors, this
has a reasonable chance of fixing the error. If the write succeeds, and a
subsequent read succeeds as well, raid5 decided the address is OK and
conitnues.
Instead of failing a drive on read-error, we attempt to re-write the block,
and then re-read. If that all works, we allow the device to remain in the
array.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/raid/raid5.h b/include/linux/raid/raid5.h
index 176fc65..f025ba6 100644
--- a/include/linux/raid/raid5.h
+++ b/include/linux/raid/raid5.h
@@ -154,6 +154,8 @@
#define R5_Wantwrite 5
#define R5_Syncio 6 /* this io need to be accounted as resync io */
#define R5_Overlap 7 /* There is a pending overlapping request on this block */
+#define R5_ReadError 8 /* seen a read error here recently */
+#define R5_ReWrite 9 /* have tried to over-write the readerror */
/*
* Write method