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path: root/include/linux/blkdev.h
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2008-02-08block: fixup rq_init() a bitJens Axboe
Rearrange fields in cache order and initialize some fields that we didn't previously init. Remove init of ->completion_data, it's part of a union with ->hash. Luckily clearing the rb node is the same as setting it to null! Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-02-01block: kill swap_io_context()Jens Axboe
It blindly copies everything in the io_context, including the lock. That doesn't work so well for either lock ordering or lockdep. There seems zero point in swapping io contexts on a request to request merge, so the best point of action is to just remove it. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-02-01block: new end request handling interface should take unsigned byte countsJens Axboe
No point in passing signed integers as the byte count, they can never be negative. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-01-29block: fix warning on compile with CONFIG_BLOCKJens Axboe
struct io_context was not defined, just add an empty forward decl. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-01-29Merge branch 'for-2.6.25' of git://git.kernel.dk/linux-2.6-blockLinus Torvalds
* 'for-2.6.25' of git://git.kernel.dk/linux-2.6-block: block: implement drain buffers __bio_clone: don't calculate hw/phys segment counts block: allow queue dma_alignment of zero blktrace: Add blktrace ioctls to SCSI generic devices
2008-01-29Merge branch 'blk-end-request' of git://git.kernel.dk/linux-2.6-blockLinus Torvalds
* 'blk-end-request' of git://git.kernel.dk/linux-2.6-block: (30 commits) blk_end_request: changing xsysace (take 4) blk_end_request: changing ub (take 4) blk_end_request: cleanup of request completion (take 4) blk_end_request: cleanup 'uptodate' related code (take 4) blk_end_request: remove/unexport end_that_request_* (take 4) blk_end_request: changing scsi (take 4) blk_end_request: add bidi completion interface (take 4) blk_end_request: changing ide-cd (take 4) blk_end_request: add callback feature (take 4) blk_end_request: changing ide normal caller (take 4) blk_end_request: changing cpqarray (take 4) blk_end_request: changing cciss (take 4) blk_end_request: changing ide-scsi (take 4) blk_end_request: changing s390 (take 4) blk_end_request: changing mmc (take 4) blk_end_request: changing i2o_block (take 4) blk_end_request: changing viocd (take 4) blk_end_request: changing xen-blkfront (take 4) blk_end_request: changing viodasd (take 4) blk_end_request: changing sx8 (take 4) ...
2008-01-28block: implement drain buffersJames Bottomley
These DMA drain buffer implementations in drivers are pretty horrible to do in terms of manipulating the scatterlist. Plus they're being done at least in drivers/ide and drivers/ata, so we now have code duplication. The one use case for this, as I understand it is AHCI controllers doing PIO mode to mmc devices but translating this to DMA at the controller level. So, what about adding a callback to the block layer that permits the adding of the drain buffer for the problem devices. The idea is that you'd do this in slave_configure after you find one of these devices. The beauty of doing it in the block layer is that it quietly adds the drain buffer to the end of the sg list, so it automatically gets mapped (and unmapped) without anything unusual having to be done to the scatterlist in driver/scsi or drivers/ata and without any alteration to the transfer length. Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-01-28io context sharing: preliminary supportJens Axboe
Detach task state from ioc, instead keep track of how many processes are accessing the ioc. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-01-28ioprio: move io priority from task_struct to io_contextJens Axboe
This is where it belongs and then it doesn't take up space for a process that doesn't do IO. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-01-28blk_end_request: cleanup 'uptodate' related code (take 4)Kiyoshi Ueda
This patch converts 'uptodate' arguments of no longer exported interfaces, end_that_request_first/last, to 'error', and removes internal conversions for it in blk_end_request interfaces. Also, this patch removes no longer needed end_io_error(). Cc: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-01-28blk_end_request: remove/unexport end_that_request_* (take 4)Kiyoshi Ueda
This patch removes the following functions: o end_that_request_first() o end_that_request_chunk() and stops exporting the functions below: o end_that_request_last() Cc: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-01-28blk_end_request: add bidi completion interface (take 4)Kiyoshi Ueda
This patch adds a variant of the interface, blk_end_bidi_request(), which completes a bidi request. Bidi request must be completed as a whole, both rq and rq->next_rq at once. So the interface has 2 arguments for completion size. As for ->end_io, only rq->end_io is called (rq->next_rq->end_io is not called). So if special completion handling is needed, the handler must be set to rq->end_io. And the handler must take care of freeing next_rq too, since the interface doesn't care of it if rq->end_io is not NULL. Cc: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-01-28blk_end_request: add callback feature (take 4)Kiyoshi Ueda
This patch adds a variant of the interface, blk_end_request_callback(), which has driver callback feature. Drivers may need to do special works between end_that_request_first() and end_that_request_last(). For such drivers, blk_end_request_callback() allows it to pass a callback function which is called between end_that_request_first() and end_that_request_last(). This interface is only for fallback of other blk_end_request interfaces. Drivers should avoid their tricky behaviors and use other interfaces as much as possible. Currently, only one driver, ide-cd, needs this interface. So this interface should/will be removed, after the driver removes such tricky behaviors. o ide-cd (cdrom_newpc_intr()) In PIO mode, cdrom_newpc_intr() needs to defer end_that_request_last() until the device clears DRQ_STAT and raises an interrupt after end_that_request_first(). So end_that_request_first() and end_that_request_last() are called separately in cdrom_newpc_intr(). This means blk_end_request_callback() has to return without completing request even if no leftover in the request. To satisfy the requirement, callback function has return value so that drivers can tell blk_end_request_callback() to return without completing request. Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-01-28blk_end_request: add/export functions to get request size (take 4)Kiyoshi Ueda
This patch adds/exports functions to get the size of request in bytes. They are useful because blk_end_request interfaces take bytes as a completed I/O size instead of sectors. Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-01-28blk_end_request: add new request completion interface (take 4)Kiyoshi Ueda
This patch adds 2 new interfaces for request completion: o blk_end_request() : called without queue lock o __blk_end_request() : called with queue lock held blk_end_request takes 'error' as an argument instead of 'uptodate', which current end_that_request_* take. The meanings of values are below and the value is used when bio is completed. 0 : success < 0 : error Some device drivers call some generic functions below between end_that_request_{first/chunk} and end_that_request_last(). o add_disk_randomness() o blk_queue_end_tag() o blkdev_dequeue_request() These are called in the blk_end_request interfaces as a part of generic request completion. So all device drivers become to call above functions. To decide whether to call blkdev_dequeue_request(), blk_end_request uses list_empty(&rq->queuelist) (blk_queued_rq() macro is added for it). So drivers must re-initialize it using list_init() or so before calling blk_end_request if drivers use it for its specific purpose. (Currently, there is no driver which completes request without re-initializing the queuelist after used it. So rq->queuelist can be used for the purpose above.) "Normal" drivers can be converted to use blk_end_request() in a standard way shown below. a) end_that_request_{chunk/first} spin_lock_irqsave() (add_disk_randomness(), blk_queue_end_tag(), blkdev_dequeue_request()) end_that_request_last() spin_unlock_irqrestore() => blk_end_request() b) spin_lock_irqsave() end_that_request_{chunk/first} (add_disk_randomness(), blk_queue_end_tag(), blkdev_dequeue_request()) end_that_request_last() spin_unlock_irqrestore() => spin_lock_irqsave() __blk_end_request() spin_unlock_irqsave() c) spin_lock_irqsave() (add_disk_randomness(), blk_queue_end_tag(), blkdev_dequeue_request()) end_that_request_last() spin_unlock_irqrestore() => blk_end_request() or spin_lock_irqsave() __blk_end_request() spin_unlock_irqrestore() Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-01-28block: allow queue dma_alignment of zeroPete Wyckoff
Let queue_dma_alignment return 0 if it was specifically set to 0. This permits devices with no particular alignment restrictions to use arbitrary user space buffers without copying. Signed-off-by: Pete Wyckoff <pw@osc.edu> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-01-26ide: remove REQ_TYPE_ATA_CMDBartlomiej Zolnierkiewicz
Based on the earlier work by Tejun Heo. All users are gone so we can finally remove it. Cc: Tejun Heo <htejun@gmail.com> Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
2008-01-25Merge git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6Linus Torvalds
* git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6: (200 commits) [SCSI] usbstorage: use last_sector_bug flag universally [SCSI] libsas: abstract STP task status into a function [SCSI] ultrastor: clean up inline asm warnings [SCSI] aic7xxx: fix firmware build [SCSI] aacraid: fib context lock for management ioctls [SCSI] ch: remove forward declarations [SCSI] ch: fix device minor number management bug [SCSI] ch: handle class_device_create failure properly [SCSI] NCR5380: fix section mismatch [SCSI] sg: fix /proc/scsi/sg/devices when no SCSI devices [SCSI] IB/iSER: add logical unit reset support [SCSI] don't use __GFP_DMA for sense buffers if not required [SCSI] use dynamically allocated sense buffer [SCSI] scsi.h: add macro for enclosure bit of inquiry data [SCSI] sd: add fix for devices with last sector access problems [SCSI] fix pcmcia compile problem [SCSI] aacraid: add Voodoo Lite class of cards. [SCSI] aacraid: add new driver features flags [SCSI] qla2xxx: Update version number to 8.02.00-k7. [SCSI] qla2xxx: Issue correct MBC_INITIALIZE_FIRMWARE command. ...
2008-01-25ide: remove REQ_TYPE_ATA_TASKBartlomiej Zolnierkiewicz
Based on the earlier work by Tejun Heo. All users are gone so we can finally remove it. Cc: Tejun Heo <htejun@gmail.com> Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
2008-01-11[SCSI] block: Introduce new blk_queue_update_dma_alignment interfaceJames Bottomley
The purpose of this is to allow stacked alignment settings, with the ultimate queue alignment being set to the largest alignment requirement in the stack. The reason for this is so that the SCSI mid-layer can relax the default alignment requirements (which are basically causing a lot of superfluous copying to go on in the SG_IO interface) while allowing transports, devices or HBAs to add stricter limits if they need them. Acked-by: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-11-09Add UNPLUG traces to all appropriate placesAlan D. Brunelle
Added blk_unplug interface, allowing all invocations of unplugs to result in a generated blktrace UNPLUG. Signed-off-by: Alan D. Brunelle <Alan.Brunelle@hp.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-10-29[BLOCK] Fix bad sharing of tag busy list on queues with shared tag mapsJens Axboe
For the locking to work, only the tag map and tag bit map may be shared (incidentally, I was just explaining this to Nick yesterday, but I apparently didn't review the code well enough myself). But we also share the busy list! The busy_list must be queue private, or we need a block_queue_tag covering lock as well. So we have to move the busy_list to the queue. This'll work fine, and it'll actually also fix a problem with blk_queue_invalidate_tags() which will invalidate tags across all shared queues. This is a bit confusing, the low level driver should call it for each queue seperately since otherwise you cannot kill tags on just a single queue for eg a hard drive that stops responding. Since the function has no callers currently, it's not an issue. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-10-16block: convert blkdev_issue_flush() to use empty barriersJens Axboe
Then we can get rid of ->issue_flush_fn() and all the driver private implementations of that. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-10-16block: Initial support for data-less (or empty) barrier supportJens Axboe
This implements functionality to pass down or insert a barrier in a queue, without having data attached to it. The ->prepare_flush_fn() infrastructure from data barriers are reused to provide this functionality. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-10-16block: add end_queued_request() and end_dequeued_request() helpersJens Axboe
We can use this helper in the elevator core for BLKPREP_KILL, and it'll also be useful for the empty barrier patch. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-10-12[BLOCK] Move sector_div() from blkdev.h to kernel.hJens Axboe
We need it even if CONFIG_BLOCK is disabled, so move it outside of the block layer include system. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-10-10Remove flush_dry_bio_endioNeilBrown
The entire function of flush_dry_bio_endio is to undo the effects of bio_endio (when called on a barrier request). So remove the function and the call to bio_endio. This allows us to remove "bi_size" from "struct request_queue". Signed-off-by: Neil Brown <neilb@suse.de> ### Diffstat output ./block/ll_rw_blk.c | 39 ++------------------------------------- ./include/linux/blkdev.h | 1 - 2 files changed, 2 insertions(+), 38 deletions(-) diff .prev/block/ll_rw_blk.c ./block/ll_rw_blk.c Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-10-10Fix warnings with !CONFIG_BLOCKJens Axboe
Hide everything in blkdev.h with CONFIG_BLOCK isn't set, and fixup the (few) files that fail to build because they were relying on blkdev.h pulling in extra includes for them. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-10-10Stop exporting blk_rq_bio_prepNeilBrown
blk_rq_bio_prep is exported for use in exactly one place. That place can benefit from using the new blk_rq_append_bio instead. So - change dm-emc to call blk_rq_append_bio - stop exporting blk_rq_bio_prep, and - initialise rq_disk in blk_rq_bio_prep, as dm-emc needs it. Signed-off-by: Neil Brown <neilb@suse.de> diff .prev/block/ll_rw_blk.c ./block/ll_rw_blk.c Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-10-10New function blk_req_append_bioNeilBrown
ll_back_merge_fn is currently exported to SCSI where is it used, together with blk_rq_bio_prep, in exactly the same way these functions are used in __blk_rq_map_user. So move the common code into a new function (blk_rq_append_bio), and don't export ll_back_merge_fn any longer. Signed-off-by: Neil Brown <neilb@suse.de> diff .prev/block/ll_rw_blk.c ./block/ll_rw_blk.c Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-10-10Introduce rq_for_each_segment replacing rq_for_each_bioNeilBrown
Every usage of rq_for_each_bio wraps a usage of bio_for_each_segment, so these can be combined into rq_for_each_segment. We define "struct req_iterator" to hold the 'bio' and 'index' that are needed for the double iteration. Signed-off-by: Neil Brown <neilb@suse.de> Various compile fixes by me... Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-27[patch] QUEUE_FLAG_READFULL QUEUE_FLAG_WRITEFULL comment fixQi Yong
The two comments were transposed. Signed-off-by: Qi Yong <qiyong@mail.fc-cn.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-24[BLOCK] Add request_queue_t and mark it deprecatedJens Axboe
Andrew thinks I should be nice and allow outside code to at least just compile, so add the request_queue_t typedef back and mark it deprecated. It'll warn people that this type is going away soonish. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-24[BLOCK] Get rid of request_queue_t typedefJens Axboe
Some of the code has been gradually transitioned to using the proper struct request_queue, but there's lots left. So do a full sweet of the kernel and get rid of this typedef and replace its uses with the proper type. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-22[SCSI] bsg: unexport sg v3 helper functionsFUJITA Tomonori
blk_fill_sghdr_rq, blk_unmap_sghdr_rq, and blk_complete_sghdr_rq were exported for bsg, however bsg was changed to support only sg v4. Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2007-07-17CONFIG_BOUNCE to avoid useless inclusion of bounce buffer logicChristoph Lameter
The bounce buffer logic is included on systems that do not need it. If a system does not have zones like ZONE_DMA and ZONE_HIGHMEM that can lead to the use of bounce buffers then there is no need to reserve memory pools etc etc. This is true f.e. for SGI Altix. Also nicifies the Makefile and gets rid of the tricky "and" there. Signed-off-by: Christoph Lameter <clameter@sgi.com> Acked-by: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-16add a struct request pointer to the request structureFUJITA Tomonori
This adds a struct request pointer to the request structure for the second data phase (bidi for now). A request queue supporting bidi requests sets QUEUE_FLAG_BIDI. This prevents sending bidi requests to a non-bidi queue. Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-16bsg: bind bsg to request_queue instead of gendiskFUJITA Tomonori
This patch binds bsg devices to request_queue instead of gendisk. Any objects (like transport entities) can define own request_handler and create own bsg device. Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-16bsg: add a request_queue argument to scsi_cmd_ioctl()FUJITA Tomonori
bsg uses scsi_cmd_ioctl() for some SCSI/sg ioctl commands. scsi_cmd_ioctl() gets a request queue from a gendisk arguement. This prevents bsg being bound to SCSI devices that don't have a gendisk (like OSD). This adds a request_queue argument to scsi_cmd_ioctl(). The SCSI/sg ioctl commands doesn't use a gendisk so it's safe for any SCSI devices to use scsi_cmd_ioctl(). Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-16block: export blk_verify_command for SG v4FUJITA Tomonori
blk_fill_sghdr_rq doesn't work for SG v4 so verify_command needed to be exported. Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-16bsg: support for full generic block layer SG v3Jens Axboe
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-10[TRIVIAL PATCH] Kill blk_congestion_wait() stub for !CONFIG_BLOCKBenjamin Gilbert
blk_congestion_wait() doesn't exist anymore, but there's still a stub in blkdev.h for the !CONFIG_BLOCK case. Kill it. Signed-off-by: Benjamin Gilbert <bgilbert@cs.cmu.edu> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-05-09kblockd: use flush_workAndrew Morton
Switch the kblockd flushing from a global flush to a more specific flush_work(). (akpm: bypassed maintainers, sorry. There are other patches which depend on this) Cc: "Maciej W. Rozycki" <macro@linux-mips.org> Cc: David Howells <dhowells@redhat.com> Cc: Jens Axboe <axboe@suse.de> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-04-30ll_rw_blk: add io_context private pointerJens Axboe
To be used by as/cfq as they see fit. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-02-11cfq-iosched: remove cfq_io_context last_queueJens Axboe
It hasn't been used for a while, kill it off and remove the old if 0 code chunk. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2006-12-19[PATCH] Fixup blk_rq_unmap_user() APIJens Axboe
The blk_rq_unmap_user() API is not very nice. It expects the caller to know that rq->bio has to be reset to the original bio, and it will silently do nothing if that is not done. Instead make it explicit that we need to pass in the first bio, by expecting a bio argument. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2006-12-19[PATCH] Remove queue merging hooksJens Axboe
We have full flexibility of merging parameters now, so we can remove the hooks that define back/front/request merge strategies. Nobody is using them anymore. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2006-12-12[PATCH] remove blk_queue_activity_fnBoaz Harrosh
While working on bidi support at struct request level I have found that blk_queue_activity_fn is actually never used. The only user is in ide-probe.c with this code: /* enable led activity for disk drives only */ if (drive->media == ide_disk && hwif->led_act) blk_queue_activity_fn(q, hwif->led_act, drive); And led_act is never initialized anywhere. (Looking back at older kernels it was used in the PPC arch, but was removed around 2.6.18) Unless it is all for future use off course. (this patch is against linux-2.6-block.git as off 2006/12/4) Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2006-12-01[PATCH] block: support larger block pc requestsMike Christie
This patch modifies blk_rq_map/unmap_user() and the cdrom and scsi_ioctl.c users so that it supports requests larger than bio by chaining them together. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2006-10-20[PATCH] separate bdi congestion functions from queue congestion functionsAndrew Morton
Separate out the concept of "queue congestion" from "backing-dev congestion". Congestion is a backing-dev concept, not a queue concept. The blk_* congestion functions are retained, as wrappers around the core backing-dev congestion functions. This proper layering is needed so that NFS can cleanly use the congestion functions, and so that CONFIG_BLOCK=n actually links. Cc: "Thomas Maier" <balagi@justmail.de> Cc: "Jens Axboe" <jens.axboe@oracle.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: David Howells <dhowells@redhat.com> Cc: Peter Osterlund <petero2@telia.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>