dm: detect lost queue
Detect and report buggy drivers that destroy their request_queue.
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Cc: Stefan Raspl <raspl@linux.vnet.ibm.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 5dd32b8..a740a69 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -482,6 +482,13 @@
{
struct request_queue *q = bdev_get_queue(bdev);
struct io_restrictions *rs = &ti->limits;
+ char b[BDEVNAME_SIZE];
+
+ if (unlikely(!q)) {
+ DMWARN("%s: Cannot set limits for nonexistent device %s",
+ dm_device_name(ti->table->md), bdevname(bdev, b));
+ return;
+ }
/*
* Combine the device limits low.
@@ -950,7 +957,14 @@
list_for_each_entry(dd, devices, list) {
struct request_queue *q = bdev_get_queue(dd->dm_dev.bdev);
- r |= bdi_congested(&q->backing_dev_info, bdi_bits);
+ char b[BDEVNAME_SIZE];
+
+ if (likely(q))
+ r |= bdi_congested(&q->backing_dev_info, bdi_bits);
+ else
+ DMWARN_LIMIT("%s: any_congested: nonexistent device %s",
+ dm_device_name(t->md),
+ bdevname(dd->dm_dev.bdev, b));
}
return r;
@@ -963,8 +977,14 @@
list_for_each_entry(dd, devices, list) {
struct request_queue *q = bdev_get_queue(dd->dm_dev.bdev);
+ char b[BDEVNAME_SIZE];
- blk_unplug(q);
+ if (likely(q))
+ blk_unplug(q);
+ else
+ DMWARN_LIMIT("%s: Cannot unplug nonexistent device %s",
+ dm_device_name(t->md),
+ bdevname(dd->dm_dev.bdev, b));
}
}