Alasdair G Kergon wrote:
> On Tue, Oct 07, 2008 at 10:18:40PM +0100, Alasdair G Kergon wrote:
>> Meanwhile I will not be applying that patch, though I may take a patch
>> to provide clean diagnostics should a situation like this occur again.
>
> I'm thinking of something like this:
>
>
> From: Alasdair G Kergon <agk@xxxxxxxxxx>
>
> Detect and report buggy drivers that destroy their request_queue.
>
> Signed-off-by: Alasdair G Kergon <agk@xxxxxxxxxx>
> Cc: Stefan Raspl <raspl@xxxxxxxxxxxxxxxxxx>
> Cc: Jens Axboe <jens.axboe@xxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>
> ---
> drivers/md/dm-table.c | 24 ++++++++++++++++++++++--
> 1 files changed, 22 insertions(+), 2 deletions(-)
>
> Index: linux-2.6.27-rc8/drivers/md/dm-table.c
> ===================================================================
> --- linux-2.6.27-rc8.orig/drivers/md/dm-table.c 2008-10-09 14:53:35.000000000 +0100
> +++ linux-2.6.27-rc8/drivers/md/dm-table.c 2008-10-09 14:56:26.000000000 +0100
> @@ -478,6 +478,13 @@ 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.
> @@ -943,7 +950,14 @@ int dm_table_any_congested(struct dm_tab
>
> list_for_each_entry(dd, devices, list) {
> struct request_queue *q = bdev_get_queue(dd->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->bdev, b));
> }
>
> return r;
> @@ -956,8 +970,14 @@ void dm_table_unplug_all(struct dm_table
>
> list_for_each_entry(dd, devices, list) {
> struct request_queue *q = bdev_get_queue(dd->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->bdev, b));
> }
> }
>
Looks good to me!
Ciao,
Stefan
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