dm raid1: fail writes if errors are not handled and log fails

commit 5528d17de1cf1462f285c40ccaf8e0d0e4c64dc0 upstream.

If the mirror log fails when the handle_errors option was not selected
and there is no remaining valid mirror leg, writes return success even
though they weren't actually written to any device.  This patch
completes them with EIO instead.

This code path is taken:
do_writes:
	bio_list_merge(&ms->failures, &sync);
do_failures:
	if (!get_valid_mirror(ms)) (false)
	else if (errors_handled(ms)) (false)
	else bio_endio(bio, 0);

The logic in do_failures is based on presuming that the write was already
tried: if it succeeded at least on one leg (without handle_errors) it
is reported as success.

Reference: https://bugzilla.redhat.com/show_bug.cgi?id=555197

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Cc: maximilian attems <max@stro.at>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index cc9dc79b0784ad4fb0970e1db4defd0126b63e5a..6021d0a9012d53c144ea7102d11ebfda0074f01b 100644 (file)
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -659,7 +659,7 @@ static void do_writes(struct mirror_set *ms, struct bio_list *writes)
        /*
         * Dispatch io.
         */
-       if (unlikely(ms->log_failure)) {
+       if (unlikely(ms->log_failure) && errors_handled(ms)) {
                spin_lock_irq(&ms->lock);
                bio_list_merge(&ms->failures, &sync);
                spin_unlock_irq(&ms->lock);