Commit 307729c8 authored Jan 09, 2012 by NeilBrown

md/raid1: perform bad-block tests for WriteMostly devices too.



We normally try to avoid reading from write-mostly devices, but when
we do we really have to check for bad blocks and be sure not to
try reading them.

With the current code, best_good_sectors might not get set and that
causes zero-length read requests to be send down which is very
confusing.

This bug was introduced in commit d2eb35ac and so the patch
is suitable for 3.1.x and 3.2.x

Reported-and-tested-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Reported-and-tested-by: Art -kwaak- van Breemen <ard@telegraafnet.nl>
Signed-off-by: NeilBrown <neilb@suse.de>
Cc: stable@vger.kernel.org

parent f2a371c5

drivers/md/raid1.c

+10 −1

Original line number	Diff line number	Diff line
		@@ -531,8 +531,17 @@ static int read_balance(struct r1conf conf, struct r1bio r1_bio, int *max_sect
		if (test_bit(WriteMostly, &rdev->flags)) {
		/* Don't balance among write-mostly, just
		* use the first as a last resort */
		if (best_disk < 0)
		if (best_disk < 0) {
		if (is_badblock(rdev, this_sector, sectors,
		&first_bad, &bad_sectors)) {
		if (first_bad < this_sector)
		/* Cannot use this */
		continue;
		best_good_sectors = first_bad - this_sector;
		} else
		best_good_sectors = sectors;
		best_disk = disk;
		}
		continue;
		}
		/* This is a reasonable device to use. It might

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