Prev: [PATCH RFC tip/core/rcu 13/23] perf_event: __rcu annotations
Next: [PATCH] mtd: Move function mtd_to_flctl to fix build failure
From: Will Drewry on 12 May 2010 17:50
On Wed, May 12, 2010 at 3:58 PM, Alasdair G Kergon <agk(a)redhat.com> wrote:
> On Wed, May 12, 2010 at 03:30:54PM -0500, Will Drewry wrote:
>> The format is dm=minor,rwmode,begin,length,target,target,params,with,commas
>
> 1. If we go down this route, pick a format that gives access to the full
> set of allowed table formats (or which can be extended trivially to do
> so in future). �So cope with multi-line tables e.g. with a marker (empty
> field?) to start a new table line.

Sounds good. That shouldn't add any serious code complexity either.
An empty field (,,) would probably work nicely.

> 2. It would be wise to define a name and optional uuid too, so the device is
> fully visible and accessible from userspace through existing mechanisms.
> Originally the name+uuid were decoupled from the mapped device itself,
> but that got changed, though the code layout (dm-ioctl.c vs. dm.c) still
> makes them appear to be separate.

It wasn't clear how I could define those externally to the dm-ioctl code.

>> + � � char target[24];
>> + � � char target_params[256];
>
> I'm never a fan of hard-coded restrictions, but at least make them
> explicit as #defines, so people can see at a glance what to change
> if they get errors for exceeding them.

Agreed. I'll add defines or see if I can use the existing ones.
(Alternately, it might be possible to use the passed in string in place
depending on the changes.)

>> +static void __init dm_setup_drive(void)
>
> Arguably most of this code could be a helper function exported from drivers/md.

True, or I could follow the do_mounts_md model and just use the ioctl interface.
Would a parallel function to ctl_ioctl which behaved the same but didn't expect
user-sourced dm_ioctl struct be a reasonable compromise?

That'd limit the code to parsing the parameter line and calling through without
duplicating the code in dev_create and table_load to yield the same behavior.

thanks!
will
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo(a)vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
 | 
Pages: 1
Prev: [PATCH RFC tip/core/rcu 13/23] perf_event: __rcu annotations
Next: [PATCH] mtd: Move function mtd_to_flctl to fix build failure