On Tue, 26 May 2015 15:32:38 -0700 Ming Lin <mlin@xxxxxxxxxx> wrote: > On Tue, May 26, 2015 at 7:33 AM, Ming Lin <mlin@xxxxxxxxxx> wrote: > > On Mon, May 25, 2015 at 7:17 AM, Christoph Hellwig <hch@xxxxxx> wrote: > >> On Mon, May 25, 2015 at 05:54:14PM +1000, NeilBrown wrote: > >>> Did I write that? I guess I did :-( > >>> I meant *after*. Don't get rid of bio_fits_rdev until split_bio is in > >>> chunk_aligned_read(). > >> > >> I suspect the whole series could use some reordering. > > > > Nice reordering. > > I'll do this. > > Here is the reordering. > https://git.kernel.org/cgit/linux/kernel/git/mlin/linux.git/log/?h=block-generic-req > > I'll post it if you are OK. > > [PATCH 01/15] block: add blk_queue_split() > [PATCH 02/15] md: remove ->merge_bvec_fn > [PATCH 03/15] dm: remov merge functions > [PATCH 04/15] drbd: remove ->merge_bvec_fn > [PATCH 05/15] pktcdvd: remove ->merge_bvec_fn > [PATCH 06/15] rbd: remove ->merge_bvec_fn > [PATCH 07/15] bcache: remove driver private bio splitting code > [PATCH 08/15] btrfs: remove bio splitting and merge_bvec_fn() calls > [PATCH 09/15] block: call blk_queue_split() in make_request functions > [PATCH 10/15] block: kill ->merge_bvec_fn and simplify bio_add_page > [PATCH 11/15] block: remove split code in blkdev_issue_discard > [PATCH 12/15] md/raid5: get rid of bio_fits_rdev() > [PATCH 13/15] block: remove bio_get_nr_vecs() > [PATCH 14/15] fs: use helper bio_add_page() instead of open coding on > [PATCH 15/15] Documentation: update notes in biovecs about The changes to dm.c and dm.h should be in the "dm:" patch, not "md:". But I don't think the sequence is right. You cannot remove ->merge_bvec_fn for *any* stacked device until *all* devices make use of blk_queue_split() (or otherwise handle arbitrarily large bios). I think it would be easiest to: - add blk_queue_split() and call it from common code before ->make_request_fn is called. The ensure all devices can accept arbitrarily large bios. - driver-by-driver remove merge_bvec_fn and make sure the the driver can cope with arbitrary bios themselve, calling blk_queue_split in the make_request function only if needed - finally remove the call to blk_queue_split from the common code. Does that make sense to others? Thanks, NeilBrown > > > > > Thanks. > > > >> > >> patch 1: > >> > >> add ->bio_split and blk_queue_split > >> > >> patch 2..n: > >> > >> one for each non-trivial driver that implements ->merge_bvec_fn to > >> remove it and instead split bios in ->make_request. The md patch > >> to do the right thing in chunk_aligned_read goes into the general > >> md patch here. The bcache patch also goes into this series. > >> > >> patch n+1: > >> > >> - add blk_queue_split calls for remaining trivial drivers > >> > >> patch n+2: > >> > >> - remove ->merge_bvec_fn and checking of max_sectors a for all > >> drivers, simplify bio_add_page > >> > >> patch n+2: > >> > >> - remove splitting in blkdev_issue_discard > >> > >> patch n+3 > >> > >> - remove bio_fits_rdev > >> > >> patch n+4 > >> > >> - remove bio_get_nr_vecs > >> > >> patch n+4 > >> > >> - use bio_add_page > >> > >> patch n+5 > >> > >> - update documentation
Attachment:
pgpXlYHy0f92a.pgp
Description: OpenPGP digital signature
