9934c8c045
Till now block layer allowed two separate modes of request execution. A request is always acquired from the request queue via elv_next_request(). After that, drivers are free to either dequeue it or process it without dequeueing. Dequeue allows elv_next_request() to return the next request so that multiple requests can be in flight. Executing requests without dequeueing has its merits mostly in allowing drivers for simpler devices which can't do sg to deal with segments only without considering request boundary. However, the benefit this brings is dubious and declining while the cost of the API ambiguity is increasing. Segment based drivers are usually for very old or limited devices and as converting to dequeueing model isn't difficult, it doesn't justify the API overhead it puts on block layer and its more modern users. Previous patches converted all block low level drivers to dequeueing model. This patch completes the API transition by... * renaming elv_next_request() to blk_peek_request() * renaming blkdev_dequeue_request() to blk_start_request() * adding blk_fetch_request() which is combination of peek and start * disallowing completion of queued (not started) requests * applying new API to all LLDs Renamings are for consistency and to break out of tree code so that it's apparent that out of tree drivers need updating. [ Impact: block request issue API cleanup, no functional change ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: Mike Miller <mike.miller@hp.com> Cc: unsik Kim <donari75@gmail.com> Cc: Paul Clements <paul.clements@steeleye.com> Cc: Tim Waugh <tim@cyberelk.net> Cc: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com> Cc: David S. Miller <davem@davemloft.net> Cc: Laurent Vivier <Laurent@lvivier.info> Cc: Jeff Garzik <jgarzik@pobox.com> Cc: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Grant Likely <grant.likely@secretlab.ca> Cc: Adrian McMenamin <adrian@mcmen.demon.co.uk> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com> Cc: Borislav Petkov <petkovbb@googlemail.com> Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com> Cc: Alex Dubov <oakad@yahoo.com> Cc: Pierre Ossman <drzeus@drzeus.cx> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Markus Lidel <Markus.Lidel@shadowconnect.com> Cc: Stefan Weinhuber <wein@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Pete Zaitcev <zaitcev@redhat.com> Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Linux I2O Support (c) Copyright 1999 Red Hat Software
and others.
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version
2 of the License, or (at your option) any later version.
AUTHORS (so far)
Alan Cox, Building Number Three Ltd.
Core code, SCSI and Block OSMs
Steve Ralston, LSI Logic Corp.
Debugging SCSI and Block OSM
Deepak Saxena, Intel Corp.
Various core/block extensions
/proc interface, bug fixes
Ioctl interfaces for control
Debugging LAN OSM
Philip Rumpf
Fixed assorted dumb SMP locking bugs
Juha Sievanen, University of Helsinki Finland
LAN OSM code
/proc interface to LAN class
Bug fixes
Core code extensions
Auvo Häkkinen, University of Helsinki Finland
LAN OSM code
/Proc interface to LAN class
Bug fixes
Core code extensions
Taneli Vähäkangas, University of Helsinki Finland
Fixes to i2o_config
CREDITS
This work was made possible by
Red Hat Software
Funding for the Building #3 part of the project
Symbios Logic (Now LSI)
Host adapters, hints, known to work platforms when I hit
compatibility problems
BoxHill Corporation
Loan of initial FibreChannel disk array used for development work.
European Comission
Funding the work done by the University of Helsinki
SysKonnect
Loan of FDDI and Gigabit Ethernet cards
ASUSTeK
Loan of I2O motherboard
STATUS:
o The core setup works within limits.
o The scsi layer seems to almost work.
I'm still chasing down the hang bug.
o The block OSM is mostly functional
o LAN OSM works with FDDI and Ethernet cards.
TO DO:
General:
o Provide hidden address space if asked
o Long term message flow control
o PCI IOP's without interrupts are not supported yet
o Push FAIL handling into the core
o DDM control interfaces for module load etc
o Add I2O 2.0 support (Deffered to 2.5 kernel)
Block:
o Multiple major numbers
o Read ahead and cache handling stuff. Talk to Ingo and people
o Power management
o Finish Media changers
SCSI:
o Find the right way to associate drives/luns/busses
Lan:
o Performance tuning
o Test Fibre Channel code
Tape:
o Anyone seen anything implementing this ?
(D.S: Will attempt to do so if spare cycles permit)