On Wed, Aug 21 2013 at 10:50pm -0400,
Joe Jin <joe.jin@xxxxxxxxxx> wrote:
> Mikulas, thanks for you suggestions, I create new patch, can you please help
> review?
>
> Subject: dm: add map_rq define for error
>
> commit a5664da "dm ioctl: make bio or request based device type immutable"
> prevented "dmsetup wape_table" change the target type to "error" for there
> is not map_rq for error target type.
>
> Signed-off-by: Joe Jin <joe.jin@xxxxxxxxxx>
> ---
> drivers/md/dm-target.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/drivers/md/dm-target.c b/drivers/md/dm-target.c
> index 37ba5db..b690910 100644
> --- a/drivers/md/dm-target.c
> +++ b/drivers/md/dm-target.c
> @@ -131,12 +131,19 @@ static int io_err_map(struct dm_target *tt, struct bio *bio)
> return -EIO;
> }
>
> +static int io_err_map_rq(struct dm_target *ti, struct request *clone,
> + union map_info *map_context)
> +{
> + return -EIO;
> +}
> +
> static struct target_type error_target = {
> .name = "error",
> .version = {1, 1, 0},
> .ctr = io_err_ctr,
> .dtr = io_err_dtr,
> .map = io_err_map,
> + .map_rq = io_err_map_rq,
> };
>
> int __init dm_target_init(void)
> --
> 1.8.3.1
Hi Joe,
Unfortunately this isn't going to work properly. Mikulas suggested a
new "error-rq" target.
I do like the idea of a single error target that is hybrid (supports
both bio-based and request-based) but the DM core would need to be
updated to support this.
Specifically, we'd need to check if the device (and active table) is
already bio-based or request-based and select the appropriate type. If
it is a new device, default to selecting bio-based.
There are some wrappers and other logic thoughout DM core that will need
auditing too.
Mike
--
dm-devel mailing list
dm-devel@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/dm-devel
