Hello, Lev.
You wrote 2 октября 2011 г., 16:46:58:
> Is it Ok? What should store this field? If it should store provider,
> which ISSUED this bio, why g_io_request() reset it? If it should
> store provider, which will EXECUTE this bio, why geom_nop set it to
> itself provider, and why is here this field at all, as it could be
> derived from bio_from (it seems, that it is always set to
> bio_from->provider!)?
On the other hand, bio_done() is called only if bio_from is NULL,
and any bio issued with g_io_request() could not have bio_form set to
NULL:
g_io_request(struct bio *bp, struct g_consumer *cp)
{
struct g_provider *pp;
int first;
KASSERT(cp != NULL, ("NULL cp in g_io_request"));
...
bp->bio_from = cp;
...
}
void
g_io_deliver(struct bio *bp, int error)
{
struct g_consumer *cp;
struct g_provider *pp;
...
cp = bp->bio_from;
if (cp == NULL) {
bp->bio_error = error;
bp->bio_done(bp);
return;
}
...
}
I'm completely puzzled, how does it work at all! Many GEOMs set
bio_done to their done utilities, and then submit bio with
g_io_request() and it seems to work! But why?! I could not understand
this from quoted code!
--
// Black Lion AKA Lev Serebryakov <[email protected]>
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