[dm-devel] [PATCH 2/2] dm thin: support for non power of 2 pool blocksize
Joe Thornber
thornber at redhat.com
Mon Apr 30 09:55:55 UTC 2012
Hi Mike,
In general this looks good. A lot cleaner now you've dropped the
specialisation of the division. A few nit-picks below.
- Joe
On Sat, Apr 28, 2012 at 12:44:29AM -0400, Mike Snitzer wrote:
> +/*
> + * do_div wrappers that don't modify the dividend
> + */
> +static inline sector_t dm_thin_do_div(sector_t a, __u32 b)
> +{
> + sector_t r = a;
> +
> + do_div(r, b);
> + return r;
> +}
> +
> +static inline sector_t dm_thin_do_mod(sector_t a, __u32 b)
> +{
> + sector_t tmp = a;
> +
> + return do_div(tmp, b);
> +}
Please don't inline static functions. Let the compiler make the
decision.
Also those sector_t's are passed by value, so you don't need to
declare r or tmp. eg, it's enough to do this:
static sector_t dm_thin_do_div(sector_t a, __u32 b)
{
do_div(a, b);
return a;
}
static sector_t dm_thin_do_mod(sector_t a, __u32 b)
{
return do_div(a, b);
}
> @@ -1941,12 +1954,18 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
...
> + if (dm_thin_do_mod(ti->len, block_size)) {
> + ti->error = "Data device is not a multiple of block size";
> + r = -EINVAL;
> + goto out;
> + }
I don't see the need for this check. If I have a disk that isn't a
multiple of the block size why should I have to layer a linear mapping
on it to truncate it before I can use it as a data volume? Any
partial block at the end of the device is already ignored (see the
data_size calculation in pool_preresume). Is this restriction causing
some of the changes you made to the test-suite?
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