[PATCH] md: Fix 'rdev->nr_pending' count when retrying barrier requests
When retrying a failed BIO_RW_BARRIER request, we need to keep the reference
in ->nr_pending over the whole retry. Currently, we only hold the reference
if the failed request is the *last* one to finish - which is silly, because it
would normally be the first to finish.
So move the rdev_dec_pending call up into the didn't-fail branch. As the rdev
isn't used in the later code, calling rdev_dec_pending earlier doesn't hurt.
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/drivers/md/raid1.c b/drivers/md/raid1.c
index b8c13c8..4070eff 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -319,6 +319,7 @@
set_bit(BarriersNotsupp, &conf->mirrors[mirror].rdev->flags);
set_bit(R1BIO_BarrierRetry, &r1_bio->state);
r1_bio->mddev->barriers_work = 0;
+ /* Don't rdev_dec_pending in this branch - keep it for the retry */
} else {
/*
* this branch is our 'one mirror IO has finished' event handler:
@@ -365,6 +366,7 @@
}
}
}
+ rdev_dec_pending(conf->mirrors[mirror].rdev, conf->mddev);
}
/*
*
@@ -374,11 +376,9 @@
if (atomic_dec_and_test(&r1_bio->remaining)) {
if (test_bit(R1BIO_BarrierRetry, &r1_bio->state)) {
reschedule_retry(r1_bio);
- /* Don't dec_pending yet, we want to hold
- * the reference over the retry
- */
goto out;
}
+ /* it really is the end of this request */
if (test_bit(R1BIO_BehindIO, &r1_bio->state)) {
/* free extra copy of the data pages */
int i = bio->bi_vcnt;
@@ -393,8 +393,6 @@
md_write_end(r1_bio->mddev);
raid_end_bio_io(r1_bio);
}
-
- rdev_dec_pending(conf->mirrors[mirror].rdev, conf->mddev);
out:
if (to_put)
bio_put(to_put);
@@ -1414,6 +1412,7 @@
* Better resubmit without the barrier.
* We know which devices to resubmit for, because
* all others have had their bios[] entry cleared.
+ * We already have a nr_pending reference on these rdevs.
*/
int i;
clear_bit(R1BIO_BarrierRetry, &r1_bio->state);