Messages in this thread | | | Date | Sat, 26 Jan 2002 00:06:00 +0100 | From | Jens Axboe <> | Subject | Re: BIO usage questions |
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On Fri, Jan 25 2002, Badari Pulavarty wrote: > Hi, > > I have few questions on usage of "bio" in 2.5.X. > > 1) It is acceptable to use "bio" instead of "kio" for doing RAW IO > and direct IO ? Currently, "kio" are getting converted to "bio" > anywhy. why not use "bio" directly ? > > I am planning to do this. But I was wondering what are the issues > here.
Sure you can do that, you would probably have to provide quite a bit of the mapping infrastructure (or make it generic, probably Ben's work in this area would be the best way forward). But bio is a generic container for block I/O, and you are allowed to use it directly.
> 2) I don't see how to wait for a "bio" to complete. I don't see any > wait_queue in bio structure. How can I wait for bio to complete ?
allocate a private bio, and you 'own' the bi_private and bi_end_io. So you could do something ala
DECLARE_COMPLETION(wait);
bio = bio_alloc(GFP_XXX, 1); /* fill in bvec, target, etc */ bio->bi_private = &wait; bio->bi_end_io = my_end_io;
...
wait_for_completion(&wait);
int my_end_io(struct bio *bio, int nr_sectors) { struct completion *wait = bio->bi_private;
/* do end i/o stuff */ ...
/* wake up waiters */ complete(wait); return 0; }
-- Jens Axboe
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