On Tue, Nov 01, 2016 at 07:51:27AM +0800, Ming Lei wrote: > Sorry for forgetting to mention one important point: > > - after multipage bvec is introduced, the iterated bvec pointer > still points to singlge page bvec, which is generated in-flight > and is readonly actually. That is the motivation about the introduction > of bio_for_each_segment_all_rd(). > > So maybe bio_for_each_page_all_ro() is better? > > For _wt(), we still can keep it as bio_for_each_segment(), which also > reflects that now the iterated bvec points to one whole segment if > we name _rd as bio_for_each_page_all_ro(). I'm agnostic as to what the right names are --- my big concern is there is an explosion of bio_for_each_page_* functions, and that there isn't good documentation about (a) when to use each of these functions, and (b) why. I was goinig through the patch series, and it was hard for me to figure out why, and I was looking through all of the patches. Once all of the patches are merged in, I am concerned this is going to be massive trapdoor that will snare a large number of unwitting developers. As far as my preference, from an abstract perspective, if one version (the read-write variant, I presume) is always safe, while one (the read-only variant) is faster, if you can work under restricted circumstances, naming the safe version so it is the "default", and more dangerous one with the name that makes it a bit more obvious what you have to do in order to use it safely, and then very clearly document both in sources, and in the Documentation directory, what the issues are and what you have to do in order to use the faster version. Cheers, - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
