Currently we fail if someone requests a valid io scheduler, but it's
modular and not currently loaded. That can happen from a driver init
asking for a different scheduler, or online switching through sysfs
as requested by a user.
This patch makes elevator_get() request_module() to attempt to load
the appropriate module, instead of requiring that done manually.
Signed-off-by: Jens 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: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Now that the old kobject_init() function is gone, rename
kobject_init_ng() to kobject_init() to clean up the namespace.
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Now that the old kobject_add() function is gone, rename kobject_add_ng()
to kobject_add() to clean up the namespace.
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This converts the code to use the new kobject functions, cleaning up the
logic in doing so.
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
elv_register() always returns 0, and there isn't anything it does where
it should return an error (the only error condition is so grave that
it's handled with a BUG_ON).
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Jens 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: Jens 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: Jens Axboe <jens.axboe@oracle.com>
A number of different drivers incorrect access the kobject name field
directly. This is not correct as the name might not be in the array.
Use the proper accessor function instead.
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>
kmalloc_node() and kmem_cache_alloc_node() were not available in a zeroing
variant in the past. But with __GFP_ZERO it is possible now to do zeroing
while allocating.
Use __GFP_ZERO to remove the explicit clearing of memory via memset whereever
we can.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Booting 2.6.21-rc3-g45592145 I noticed the following on one of my
machines in the bootlog:
io scheduler noop registered<6>Time: jiffies clocksource has been installed.
io scheduler deadline registered (default)
Looking at block/elevator.c, it appears that elv_register() uses two
consecutive printks in a non-atomic way, leading to the above glitch. The
attached trivial patch fixes this issue, by using a single printk.
Signed-off-by: Thibaut VARENE <varenet@parisc-linux.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
A flag was recently added to the elevator code to avoid
performing an unplug when reuests are being re-queued.
The goal of this flag was to avoid a deep recursion that
can occur when re-queueing requests after a SCSI device/host
reset. See http://lkml.org/lkml/2006/5/17/254
However, that fix added the flag near the bottom of a case
statement, where an earlier break (in an if statement) could
transport one out of the case, without setting the flag.
This patch sets the flag earlier in the case statement.
I re-discovered the deep recursion recently during testing;
I was told that it was a known problem, and the fix to it was
in the kernel I was testing. Indeed it was ... but it didn't
fix the bug. With the patch below, I no longer see the bug.
Signed-off by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Jens Axboe <axboe@suse.de>
Cc: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The recent io scheduler allow_merge commit left the block layer with
no merging, oops. This patch fixes that up.
That means the CFQ change needs to be verified again, it might not fix
the original bug now. But that's a seperate thing, I'll double check
that tomorrow.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Currently we allow any merge, even if the io originates from different
processes. This can cause really bad starvation and unfairness, if those
ios happen to be synchronous (reads or direct writes).
So add a allow_merge hook to the io scheduler ops, so an io scheduler can
help decide whether a bio/process combination may be merged with an
existing request.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
- ->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: Jens Axboe <jens.axboe@oracle.com>
elv_iosched_show function iterates other elv_list, hence
elv_list_lock should be got.
Signed-off-by: Vasily Tarasov <vtaras@openvz.org>
Signed-off-by: Vasily Tarasov <jens.axboe@oracle.com>
We can easily produce search through the elevator list
without introducing additional elevator_type variable.
Signed-off-by: Vasily Tarasov <vtaras@openvz.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
