On Sat, Nov 12, 2016 at 09:42:38AM -0800, Christoph Hellwig wrote: > On Fri, Nov 11, 2016 at 11:02:23AM -0800, Shaohua Li wrote: > > > It's mostly about the RAID1 and RAID10 code which does a lot of funny > > > things with the bi_iov_vec and bi_vcnt fields, which we'd prefer that > > > drivers don't touch. One example is the r1buf_pool_alloc code, > > > which I think should simply use bio_clone for the MD_RECOVERY_REQUESTED > > > case, which would also take care of r1buf_pool_free. I'm not sure > > > about all the others cases, as some bits don't fully make sense to me, > > > > The problem is we use the iov_vec to track the pages allocated. We will read > > data to the pages and write out later for resync. If we add new fields to track > > the pages in r1bio, we could use standard API bio_kmalloc/bio_add_page and > > avoid the tricky parts. This should work for both the resync and writebehind > > cases. > > I don't think we need to track the pages specificly - if we clone > a bio we share the bio_vec, e.g. for the !MD_RECOVERY_REQUESTED > we do one bio_kmalloc, then bio_alloc_pages then clone it for the > others bios. for MD_RECOVERY_REQUESTED we do a bio_kmalloc + > bio_alloc_pages for each. Sure, for r1buf_pool_alloc, what you suggested should work well. There are a lot of other places we are using bi_vcnt/bi_io_vec. I'm not sure if it's easy to replace them with bio iterator. But having a separate data structue to track the memory we read/rewite/sync and so on definitively will make things easier. I'm not saying to add the extra data structure in bio but instead in r1bio. Thanks, Shaohua -- 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
