From: Alasdair G Kergon Detect and report buggy drivers that destroy their request_queue. Signed-off-by: Alasdair G Kergon Cc: Stefan Raspl Cc: Jens Axboe Cc: Andrew Morton --- drivers/md/dm-table.c | 24 ++++++++++++++++++++++-- 1 files changed, 22 insertions(+), 2 deletions(-) Index: linux-2.6.27/drivers/md/dm-table.c =================================================================== --- linux-2.6.27.orig/drivers/md/dm-table.c 2008-10-10 12:21:38.000000000 +0100 +++ linux-2.6.27/drivers/md/dm-table.c 2008-10-10 12:21:42.000000000 +0100 @@ -482,6 +482,13 @@ void dm_set_device_limits(struct dm_targ { 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 @@ int dm_table_any_congested(struct dm_tab 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 @@ void dm_table_unplug_all(struct dm_table 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)); } }