Move some functions out of the buffering code that aren't strictly buffering
specific.  This is a precursor to being able to disable the block layer.

 (*) Moved some stuff out of fs/buffer.c:

     (*) The file sync and general sync stuff moved to fs/sync.c.

     (*) The superblock sync stuff moved to fs/super.c.

     (*) do_invalidatepage() moved to mm/truncate.c.

     (*) try_to_release_page() moved to mm/filemap.c.

 (*) Moved some related declarations between header files:

     (*) declarations for do_invalidatepage() and try_to_release_page() moved
     	 to linux/mm.h.

     (*) __set_page_dirty_buffers() moved to linux/buffer_head.h.
Signed-Off-By: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This patch kills a few lines of code in blktrace by making use of
on_each_cpu().
Signed-off-by: NMartin Peschke <mp3@de.ibm.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We don't need to disable irqs to clear current->io_context, it is protected
by ->alloc_lock. Even IF it was possible to submit I/O from IRQ on behalf of
current this irq_disable() can't help: current_io_context() will re-instantiate
->io_context after irq_enable().

We don't need task_lock() or local_irq_disable() to clear ioc->task. This can't
prevent other CPUs from playing with our io_context anyway.
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

It is a leftover from before the softirq completion was migrated
to the block layer.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

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

Give meta data reads preference over regular reads, as the process
often needs to get that out of the way to do the io it was actually
interested in.
Signed-off-by: NJens Axboe <axboe@suse.de>

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

We can use this information for making more intelligent priority
decisions, and it will also be useful for blktrace.
Signed-off-by: NJens Axboe <axboe@suse.de>

It can make sense to set read-ahead larger than a single request.
We should not be enforcing such policy on the user. Additionally,
using the BLKRASET ioctl doesn't impose such a restriction. So
additionally we now expose identical behaviour through the two.

Issue also reported by Anton <cbou@mail.ru>
Signed-off-by: NJens Axboe <axboe@suse.de>

Don't touch the current queues, just make sure that the wanted queue
is selected next. Simplifies the logic.
Signed-off-by: NJens Axboe <axboe@suse.de>

CFQ implements this on its own now, but it's really block layer
knowledge. Tells a device queue to start dispatching requests to
the driver, taking care to unplug if needed. Also fixes the issue
where as/cfq will invoke a stopped queue, which we really don't
want.
Signed-off-by: NJens Axboe <axboe@suse.de>

No point in having a place holder list just for empty queues, so remove
it. It's not used for anything other than to keep ->cfq_list busy.
Signed-off-by: NJens Axboe <axboe@suse.de>

Currently it scales with number of processes in that priority group,
which is potentially not very nice as it's called quite often.
Basically we always need to do tail inserts, except for the case of a
new process. So just mark/detect a queue as such.
Signed-off-by: NJens Axboe <axboe@suse.de>

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

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

Kill a few inlines that bring in too much code to more than one location
Shrinks kernel text by about 300 bytes on 32-bit x86.
Signed-off-by: NJens Axboe <axboe@suse.de>

It's ok if the read path is a lot more costly, as long as inc/dec is
really cheap. The inc/dec will happen for each created/freed io context,
while the reading only happens when a disk queue exits.
Signed-off-by: NJens Axboe <axboe@suse.de>

It's ok if the read path is a lot more costly, as long as inc/dec is
really cheap. The inc/dec will happen for each created/freed io context,
while the reading only happens when a disk queue exits.
Signed-off-by: NJens Axboe <axboe@suse.de>

None of the in-kernel primitives for handling "atomic" counting seem
to be a good fit. We need something that is essentially free for
incrementing/decrementing, while the read side may be more expensive
as we only ever need to do that when a device is removed from the
kernel.

Use a per-cpu variable for maintaining a per-cpu ioc count and define
a reading mechanism that just sums up the values.
Signed-off-by: NJens Axboe <axboe@suse.de>

cfq_exit_lock is protecting two things now:

- The per-ioc rbtree of cfq_io_contexts

- The per-cfqd linked list of cfq_io_contexts

The per-cfqd linked list can be protected by the queue lock, as it is (by
definition) per cfqd as the queue lock is.

The per-ioc rbtree is mainly used and updated by the process itself only.
The only outside use is the io priority changing. If we move the
priority changing to not browsing the rbtree, we can remove any locking
from the rbtree updates and lookup completely. Let the sys_ioprio syscall
just mark processes as having the iopriority changed and lazily update
the private cfq io contexts the next time io is queued, and we can
remove this locking as well.
Signed-off-by: NJens Axboe <axboe@suse.de>

A collection of little fixes and cleanups:

- We don't use the 'queued' sysfs exported attribute, since the
  may_queue() logic was rewritten. So kill it.

- Remove dead defines.

- cfq_set_active_queue() can be rewritten cleaner with else if conditions.

- Several places had cfq_exit_cfqq() like logic, abstract that out and
  use that.

- Annotate the cfqq kmem_cache_alloc() so the allocator knows that this
  is a repeat allocation if it fails with __GFP_WAIT set. Allows the
  allocator to start freeing some memory, if needed. CFQ already loops for
  this condition, so might as well pass the hint down.

- Remove cfqd->rq_starved logic. It's not needed anymore after we dropped
  the crq allocation in cfq_set_request().

- Remove uneeded parameter passing.
Signed-off-by: NJens Axboe <axboe@suse.de>

Move some members around and unionize completion_data and rb_node since
they cannot ever be used at the same time.
Signed-off-by: NJens Axboe <axboe@suse.de>

- Don't assign variables that are only used once.

- Kill spin_lock() prefetching, it's opportunistic at best.
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>

After Christophs SCSI change, the only usage left is RQ_ACTIVE
and RQ_INACTIVE. The block layer sets RQ_INACTIVE right before freeing
the request, so any check for RQ_INACTIVE in a driver is a bug and
indicates use-after-free.

So kill/clean the remaining users, straight forward.
Signed-off-by: NJens Axboe <axboe@suse.de>

It is always identical to &q->rq, and we only use it for detecting
whether this request came out of our mempool or not. So replace it
with an additional ->flags bit flag.
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>

Get rid of the as_rq request type. With the added elevator_private2, we
have enough room in struct request to get rid of any arq allocation/free
for each request.
Signed-off-by: NJens Axboe <axboe@suse.de>
Signed-off-by: NNick Piggin <npiggin@suse.de>

Get rid of the cfq_rq request type. With the added elevator_private2, we
have enough room in struct request to get rid of any crq allocation/free
for each request.
Signed-off-by: NJens Axboe <axboe@suse.de>

Then we have enough room in the request to get rid of the dynamic
allocations in CFQ/AS.
Signed-off-by: NJens Axboe <axboe@suse.de>

There's just one flag currently (SYNC), and that one can be grabbed from
the request.
Signed-off-by: NJens Axboe <axboe@suse.de>

A big win, we now save an allocation/free on each request! With the
previous rb/hash abstractions, we can just reuse queuelist/donelist
for the FIFO data and be done with it.
Signed-off-by: NJens Axboe <axboe@suse.de>

We can track this in struct request.
Signed-off-by: NJens Axboe <axboe@suse.de>
Signed-off-by: NNick Piggin <npiggin@suse.de>

Saves some space in arq.
Signed-off-by: NJens Axboe <axboe@suse.de>
Signed-off-by: NNick Piggin <npiggin@suse.de>

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

The io schedulers can use this instead of having to allocate space for
it themselves.
Signed-off-by: NJens Axboe <axboe@suse.de>

This removes the rbtree handling from deadline.
Signed-off-by: NJens Axboe <axboe@suse.de>

This removes the rbtree handling from CFQ.
Signed-off-by: NJens Axboe <axboe@suse.de>

This removes the rbtree handling from AS.
Signed-off-by: NJens Axboe <axboe@suse.de>
Signed-off-by: NNick Piggin <npiggin@suse.de>