On Mon, 1 Oct 2012 18:59:12 -0700
Ed Cashin <ecas...@coraid.com> wrote:
> The ATA over Ethernet protocol uses a major (shelf) and
> minor (slot) address to identify a particular storage target.
> These changes remove an artificial limitation the aoe driver
> imposes on the use of AoE addresses. For example, without these
> changes, the slot address has a maximum of 15, but users commonly
> use slot numbers much greater than that.
>
> The AoE shelf and slot address space is often used sparsely.
> Instead of using a static mapping between AoE addresses and the
> block device minor number, the block device minor numbers are now
> allocated on demand.
>
> ...
Very minor things...
>
> ...
>
> +static int
> +minor_get(ulong *minor)
> {
> - struct aoedev *d;
> ulong flags;
> + ulong n;
> + int error = 0;
> +
> + spin_lock_irqsave(&used_minors_lock, flags);
> + n = find_first_zero_bit(used_minors, N_DEVS);
> + if (n < N_DEVS)
> + set_bit(n, used_minors);
> + else
> + error = -1;
> + spin_unlock_irqrestore(&used_minors_lock, flags);
> +
> + *minor = n * AOE_PARTITIONS;
> + return error;
> +}
- can use the more efficient __set_bit() inside that spinlock.
- could avoid setting *minor if we're returning an error.
> - spin_lock_irqsave(&devlist_lock, flags);
> +static void
> +minor_free(ulong minor)
> +{
> + ulong flags;
>
> - for (d=devlist; d; d=d->next)
> - if (d->aoemajor == maj && d->aoeminor == min) {
> - d->ref++;
> - break;
> - }
> + minor /= AOE_PARTITIONS;
> + BUG_ON(minor >= N_DEVS);
>
> - spin_unlock_irqrestore(&devlist_lock, flags);
> - return d;
> + spin_lock_irqsave(&used_minors_lock, flags);
> + BUG_ON(!test_bit(minor, used_minors));
> + clear_bit(minor, used_minors);
> + spin_unlock_irqrestore(&used_minors_lock, flags);
> }
Could use
BUG_ON(!__test_and_clear_bit(...));
This will work, but I think it's bad form to put an expression with
side-effects inside an assert macro.
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