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 d2eb35acfd 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
This commit is contained in:
NeilBrown 2012-01-09 01:41:51 +11:00
parent f2a371c5e7
commit 307729c8bc

View File

@ -531,8 +531,17 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect
if (test_bit(WriteMostly, &rdev->flags)) { if (test_bit(WriteMostly, &rdev->flags)) {
/* Don't balance among write-mostly, just /* Don't balance among write-mostly, just
* use the first as a last resort */ * 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; best_disk = disk;
}
continue; continue;
} }
/* This is a reasonable device to use. It might /* This is a reasonable device to use. It might