- ->init_queue() does not need the elevator passed in
- ->put_request() is a hot path and need not have the queue passed in
- cfq_update_io_seektime() does not need cfqd passed in
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

elv_iosched_show function iterates other elv_list, hence
elv_list_lock should be got.
Signed-off-by: NVasily Tarasov <vtaras@openvz.org>
Signed-off-by: NVasily Tarasov <jens.axboe@oracle.com>

We can easily produce search through the elevator list
without introducing additional elevator_type variable.
Signed-off-by: NVasily Tarasov <vtaras@openvz.org>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

As people often look for the copyright in files to see who to mail,
update the link to a neutral one.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Some were kmalloc_node(), some were still kmalloc(). Change them all to
kmalloc_node().
Signed-off-by: NJens Axboe <axboe@suse.de>

It's not needed for anything, so kill the bio passing.
Signed-off-by: NJens Axboe <axboe@suse.de>

As the comments indicates in blkdev.h, we can fold it into ->end_io_data
usage as that is really what ->waiting is. Fixup the users of
blk_end_sync_rq().
Signed-off-by: NJens Axboe <axboe@kernel.dk>

The rbtree sort/lookup/reposition logic is mostly duplicated in
cfq/deadline/as, so move it to the elevator core. The io schedulers
still provide the actual rb root, as we don't want to impose any sort
of specific handling on the schedulers.

Introduce the helpers and rb_node in struct request to help migrate the
IO schedulers.
Signed-off-by: NJens Axboe <axboe@suse.de>

Right now, every IO scheduler implements its own backmerging (except for
noop, which does no merging). That results in duplicated code for
essentially the same operation, which is never a good thing. This patch
moves the backmerging out of the io schedulers and into the elevator
core. We save 1.6kb of text and as a bonus get backmerging for noop as
well. Win-win!
Signed-off-by: NJens Axboe <axboe@suse.de>

Right now ->flags is a bit of a mess: some are request types, and
others are just modifiers. Clean this up by splitting it into
->cmd_type and ->cmd_flags. This allows introduction of generic
Linux block message types, useful for sending generic Linux commands
to block devices.
Signed-off-by: NJens Axboe <axboe@suse.de>

An exiting task or process which didn't do I/O yet have no io context,
elv_unregister() should check it is not NULL.
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Acked-by: NJens Axboe <axboe@suse.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Signed-off-by: NJörn Engel <joern@wohnheim.fh-wedel.de>
Signed-off-by: NAdrian Bunk <bunk@stusta.de>

We already drop the refcount in elevator_exit(), and as
we're setting 'e' to NULL, we'll never take that branch anyway.
Finally, as 'e' is a local var that isn't referenced afterwards,
setting it to NULL is pointless.
Signed-off-by: NDave Jones <davej@redhat.com>
Signed-off-by: NJens Axboe <axboe@suse.de>

There's a race between shutting down one io scheduler and firing up the
next, in which a new io could enter and cause the io scheduler to be
invoked with bad or NULL data.

To fix this, we need to maintain the queue lock for a bit longer.
Unfortunately we cannot do that, since the elevator init requires to be
run without the lock held.  This isn't easily fixable, without also
changing the mempool API.  So split the initialization into two parts,
and alloc-init operation and an attach operation.  Then we can
preallocate the io scheduler and related structures, and run the attach
inside the lock after we detach the old one.

This patch has survived 30 minutes of 1 second io scheduler switching
with a very busy io load.
Signed-off-by: NJens Axboe <axboe@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Don't recurse back into the driver even if the unplug threshold is met,
when the driver asks for a requeue. This is both silly from a logical
point of view (requeues typically happen due to driver/hardware
shortage), and also dangerous since we could hit an endless request_fn
-> requeue -> unplug -> request_fn loop and crash on stack overrun.

Also limit blk_run_queue() to one level of recursion, similar to how
blk_start_queue() works.

This patch fixed a real problem with SLES10 and lpfc, and it could hit
any SCSI lld that returns non-zero from it's ->queuecommand() handler.
Signed-off-by: NJens Axboe <axboe@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch removes the following unused EXPORT_SYMBOL's:
- elv_requeue_request
- elv_completed_request

They are only used by the block core, hence they need not be exported.
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Signed-off-by: NJens Axboe <axboe@suse.de>

The boot cmdline is parsed in parse_early_param() and
parse_args(,unknown_bootoption).

And __setup() is used in obsolete_checksetup().

	start_kernel()
		-> parse_args()
			-> unknown_bootoption()
				-> obsolete_checksetup()

If __setup()'s callback (->setup_func()) returns 1 in
obsolete_checksetup(), obsolete_checksetup() thinks a parameter was
handled.

If ->setup_func() returns 0, obsolete_checksetup() tries other
->setup_func().  If all ->setup_func() that matched a parameter returns 0,
a parameter is seted to argv_init[].

Then, when runing /sbin/init or init=app, argv_init[] is passed to the app.
If the app doesn't ignore those arguments, it will warning and exit.

This patch fixes a wrong usage of it, however fixes obvious one only.
Signed-off-by: NOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

this changes if() BUG(); constructs to BUG_ON() which is
cleaner, contains unlikely() and can better optimized away.
Signed-off-by: NEric Sesterhenn <snakebyte@gmx.de>
Signed-off-by: NAdrian Bunk <bunk@stusta.de>

Signed-off-by: NJens Axboe <axboe@suse.de>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

q->ordcolor must only be flipped on initial queueing of a hardbarrier
request.

Constructing ordered sequence and requeueing used to pass through
__elv_add_request() which flips q->ordcolor when it sees a barrier
request.

This patch separates out elv_insert() from __elv_add_request() and uses
elv_insert() when constructing ordered sequence and requeueing.
elv_insert() inserts the given request at the specified position and
does nothing else.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Acked-by: NJens Axboe <axboe@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

q->ordcolor must not be flipped on SOFTBARRIER.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Acked-by: NJens Axboe <axboe@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Jens has decided that allowing the default scheduler to be a module is
a bug, and should not be allowed under kconfig.  However, I find that
scenario useful for debugging, and wish for the kernel to be able to
handle this situation without OOPSing, if I enable such an option in
the .config directly.  This patch dynamically checks for the presence
of the compiled-in default, and falls back to no-op, emitting a
suitable error message, when the default is not available

Tested for a range of boot options on 2.6.16-rc1-mm2.
Signed-off-by: NNate Diller <nate.diller@gmail.com>
Signed-off-by: NJens Axboe <axboe@suse.de>

My previous default iosched patch did a poor job dealing with the
'elevator=' boot-time option.  The old behavior falls back to the
compiled-in default if the requested one is not registered at boot
time.  This patch dynamically evaluates which default
to use, and emits a suitable error message when the requested scheduler
is not available.  It also does the 'as' -> 'anticipatory' conversion
before elevator registration, which along with a modified registration
function, allows it to correctly indicate which default scheduler is
in use.

Tested for a range of boot options on 2.6.16-rc1-mm2.
Signed-off-by: NNate Diller <nate.diller@gmail.com>
Signed-off-by: NJens Axboe <axboe@suse.de>

As of 2.6.15 you need to use "anticipatory" instead of "as".  Fix that up
so that `elevator=as' still works.
Signed-off-by: NChuck Ebbert <76306.1226@compuserve.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Jens Axboe <axboe@suse.de>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Signed-off-by: NJens Axboe <axboe@suse.de>

Signed-off-by: NChuck Ebbert <76306.1226@compuserve.com>
Signed-off-by: NJens Axboe <axboe@suse.de>

If ordered tag isn't supported, request ordering for barrier
sequencing is performed by queue draining, which basically hangs the
request queue until elv_completed_request() reports completion of all
previous fs requests.

The condition check in elv_completed_request() was only performed for
fs requests.  If a special request is queued between the last
to-be-drained request and the barrier sequence, draining is never
completed and the queue is stalled forever.

This patch moves the end-of-draining condition check such that it's
performed for all requests.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJens Axboe <axboe@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

elv_try_last_merge().
Signed-off-by: NCoywolf Qi Hunt <qiyong@fc-cn.com>
Signed-off-by: NJens Axboe <axboe@suse.de>

Reimplement handling of barrier requests.

* Flexible handling to deal with various capabilities of
  target devices.
* Retry support for falling back.
* Tagged queues which don't support ordered tag can do ordered.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJens Axboe <axboe@suse.de>

add @uptodate argument to end_that_request_last() and @error
to rq_end_io_fn().  there's no generic way to pass error code
to request completion function, making generic error handling
of non-fs request difficult (rq->errors is driver-specific and
each driver uses it differently).  this patch adds @uptodate
to end_that_request_last() and @error to rq_end_io_fn().

for fs requests, this doesn't really matter, so just using the
same uptodate argument used in the last call to
end_that_request_first() should suffice.  imho, this can also
help the generic command-carrying request jens is working on.
Signed-off-by: Ntejun heo <htejun@gmail.com>
Signed-Off-By: NJens Axboe <axboe@suse.de>

Some leftover comments referring to drivers/block that are now block/.
They don't add any information we don't already have, so kill them.
Signed-off-by: NCoywolf Qi Hunt <qiyong@fc-cn.com>
Signed-off-by: NJens Axboe <axboe@suse.de>

With generic dispatch queue update, implicit former/latter request
handling using rq->queuelist.prev/next doesn't work as expected
anymore.  Also, the only iosched dependent on this feature was
noop-iosched and it has been reimplemented to have its own
latter/former methods.  This patch removes implicit former/latter
handling.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJens Axboe <axboe@suse.de>

elv_iosched_store doesn't terminate string passed from userspace if
it's too long.  Also, if the written length is zero (probably not
possible), it accesses elevator_name[-1].  This patch fixes both bugs.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJens Axboe <axboe@suse.de>

This patch adds request_queue->nr_sorted which keeps the number of
requests in the iosched and implement elv_drain_elevator which
performs forced dispatching.  elv_drain_elevator checks whether
iosched actually dispatches all requests it has and prints error
message if it doesn't.  As buggy forced dispatching can result in
wrong barrier operations, I think this extra check is worthwhile.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJens Axboe <axboe@suse.de>

elevator_dispatch needs to run queue after forced dispatching;
otherwise, the queue might stall.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJens Axboe <axboe@suse.de>

In addition to the first patch, which is probably goodness, I found the
cause of my panic - applying this patch fixes it and now I am booting.
If the chosen_elevator[] is not found, fall back to noop.
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NJens Axboe <axboe@suse.de>

I got a panic in the elevator code, backtrace :

Unable to handle kernel NULL pointer dereference at virtual address 00000060
..
EIP is at elevator_put+0x0/0x30 (null elevator_type passed)
..
elevator_init+0x38
blk_init_queu_node+0xc9
floppy_init+0xdb
do_initcalls+0x23
init+0x10a
init+0x0

Clearly if the kmalloc here fails, e->elevator_type is not yet set; this
appears to be the correct fix, but I think I probably hit the second case
due to a race condition.  Someone more familiar with the elevator code
should look at this more closely until I can determine if I can reproduce.
Signed-off-by: NZachary Amsden <zach@vmware.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NJens Axboe <axboe@suse.de>