Messages in this thread | | | Date | Sat, 21 Feb 2004 01:58:38 -0800 | From | Mike Christie <> | Subject | Re: [Patch 1/6] dm: endio method |
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Joe Thornber wrote:
> Add an endio method to targets. This method is allowed to request > another shot at failed ios (think multipath).
> + if (endio) { > + /* Restore bio fields. */ > + bio->bi_sector = tio->bi_sector; > + bio->bi_bdev = tio->bi_bdev; > + bio->bi_size = tio->bi_size; > + bio->bi_idx = tio->bi_idx; > + > + r = endio(tio->ti, bio, error, &tio->info);
> + r = ti->type->map(ti, clone, &tio->info); > + if (r > 0) { > + /* Save the bio info so we can restore it during endio. */ > + tio->bi_sector = clone->bi_sector; > + tio->bi_bdev = clone->bi_bdev; > + tio->bi_size = clone->bi_size; > + tio->bi_idx = clone->bi_idx;
Saving and restoring bi_bdev is going to break multipath. When a bio is remapped and resent multiple times by the target becuase of multiple path failures, restoring bi_bdev to the original value will cause only that path to be marked as failed instead of the paths that the bio was remapped to.
This is DM's cloned bio. Is there a guarantee that this value should be safe from lower level drivers overwriting it, or is it similar to b_rdev for buffer_heads?
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