Messages in this thread | | | Date | Tue, 7 Feb 2006 08:41:36 +0100 | From | Jens Axboe <> | Subject | Re: [RFC/PATCH] block: undeprecate ll_rw_block() |
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On Tue, Feb 07 2006, Pekka J Enberg wrote: > On Mon, Feb 06 2006, Pekka Enberg wrote: > > > This patch removes the DEPRECATED comment from ll_rw_block(). The function > > > is still in active use and there isn't any real replacement for it. > > On Mon, 6 Feb 2006, Jens Axboe wrote: > > It is still deprecated, so I think the comment should stay. There are > > plenty ways to accomplish what ll_rw_block does (and more efficiently, > > array of bh's is not very nice to say the least) and the buffer_head > > isn't even an io unit anymore. > > To clarify, what ways are there? When we need to access the data, use > submit_bh() and when we just want the I/O to be done, > generic_make_request()?
Generally you want to move to using a bio instead of a bh. Once you do that, you can submit > 1 page of io a lot more efficiently than what ll_rw_block() is doing. submit_bh() is just a 'wrapper' on top of the real io interface, your explanation of the two doesn't make sense.
generic_make_request() is typically something a low level driver like md or dm would use to submit a formed bio to a device, it's not something you'd expect other parts of the kernel to use. If you look at the newer io parts in the kernel (in fs/ and mm/), you'll see them using submit_bio() mostly.
-- Jens Axboe
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