Messages in this thread | | | Date | Mon, 13 Apr 2009 04:31:08 -0400 | From | Jeff Garzik <> | Subject | Re: [PATCHSET pata-2.6] ide: rq->buffer, data, special and misc cleanups |
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FUJITA Tomonori wrote: > On Mon, 13 Apr 2009 03:54:38 -0400 > Jeff Garzik <jeff@garzik.org> wrote: > >> FUJITA Tomonori wrote: >>> On Tue, 31 Mar 2009 16:04:39 +0300 >>> Boaz Harrosh <bharrosh@panasas.com> wrote: >>> >>>>> I >>>>> just don't think bvec should be used outside of block/fs interface. >>>>> As I wrote before, non-FS users have no reason to worry about bio. >>>>> All it should think about is the requst it needs to issue and the >>>>> memory area it's gonna use as in/out buffers. bio just doesn't have a >>>>> place there. >>>>> >>>> I don't understand what happens to all the people that start to work on the block >>>> layer, they start getting defensive about bio being private to the request >>>> level. But the Genie is out of the bag already (I know cats and bottles). >>>> bio is already heavily used above the block layer from directly inside filesystems >>>> to all kind of raid engines, DM MD managers, multi paths, integrity information ... >>>> >>>> Because bio is exactly that Ideal page carrier you are talking about. >>> Wrong. multi path doesn't use bio. md accesses to the bio internal >>> (it's not nice) and has the own way to carry pages. dm has the own >>> mechanism on the top of bio. And bio doesn't work nicely for file >>> systems such as btrfs, which handle multiple devices. >>> >>> Please stop your wrong argument 'bio is the ideal page carrier'. >> What is the multi-device problem with bio? > > Well, if it works nicely, I guess that we don't have something like > drivers/dm/{dm-bio-record.h, dm-bio-list.h}, btrfs_multi_bio struct, > or md's own page carrier?
It was an honest question. I am seeking information, not denying your argument.
What, specifically, is this multi-device problem with bio, please?
Jeff
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