Draining shouldn't be done for commands where overflow may indicate
data integrity issues.  Add dma_drain_needed callback to
request_queue.  Drain buffer is appened iff this function returns
non-zero.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

With padding and draining moved into it, block layer now may extend
requests as directed by queue parameters, so now a request has two
sizes - the original request size and the extended size which matches
the size of area pointed to by bios and later by sgs.  The latter size
is what lower layers are primarily interested in when allocating,
filling up DMA tables and setting up the controller.

Both padding and draining extend the data area to accomodate
controller characteristics.  As any controller which speaks SCSI can
handle underflows, feeding larger data area is safe.

So, this patch makes the primary data length field, request->data_len,
indicate the size of full data area and add a separate length field,
request->raw_data_len, for the unmodified request size.  The latter is
used to report to higher layer (userland) and where the original
request size should be fed to the controller or device.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

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: NJens Axboe <jens.axboe@oracle.com>

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: NJens Axboe <jens.axboe@oracle.com>

No point in passing signed integers as the byte count, they can never
be negative.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

struct io_context was not defined, just add an empty forward decl.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

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: NJames Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Detach task state from ioc, instead keep track of how many processes
are accessing the ioc.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

This is where it belongs and then it doesn't take up space for a
process that doesn't do IO.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

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: NKiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: NJun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

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: NKiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: NJun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

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: NKiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: NJun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

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: NKiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: NJun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

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: NKiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: NJun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

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: NKiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: NJun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

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: NPete Wyckoff <pw@osc.edu>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

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: NBartlomiej Zolnierkiewicz <bzolnier@gmail.com>

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: NBartlomiej Zolnierkiewicz <bzolnier@gmail.com>

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: NJens Axboe <jens.axboe@oracle.com>
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>

Added blk_unplug interface, allowing all invocations of unplugs to result
in a generated blktrace UNPLUG.
Signed-off-by: NAlan D. Brunelle <Alan.Brunelle@hp.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

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: NJens Axboe <jens.axboe@oracle.com>

Then we can get rid of ->issue_flush_fn() and all the driver private
implementations of that.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

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: NJens Axboe <jens.axboe@oracle.com>

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: NJens Axboe <jens.axboe@oracle.com>

We need it even if CONFIG_BLOCK is disabled, so move it outside of
the block layer include system.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

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: NNeil 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: NJens Axboe <jens.axboe@oracle.com>

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: NJens Axboe <jens.axboe@oracle.com>

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: NNeil Brown <neilb@suse.de>

diff .prev/block/ll_rw_blk.c ./block/ll_rw_blk.c
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

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: NNeil Brown <neilb@suse.de>

diff .prev/block/ll_rw_blk.c ./block/ll_rw_blk.c
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

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: NNeil Brown <neilb@suse.de>

Various compile fixes by me...
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

The two comments were transposed.
Signed-off-by: NQi Yong <qiyong@mail.fc-cn.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

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: NJens Axboe <jens.axboe@oracle.com>

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: NJens Axboe <jens.axboe@oracle.com>

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: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

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: NChristoph Lameter <clameter@sgi.com>
Acked-by: NJens Axboe <jens.axboe@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

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: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

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: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

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: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

blk_fill_sghdr_rq doesn't work for SG v4 so verify_command needed to
be exported.
Signed-off-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Signed-off-by: NJens Axboe <jens.axboe@oracle.com>