linux-toradex.git/include/linux/blkdev.h, branch v4.10-rc1

block: Remove unused member (busy) from struct blk_queue_tag

2016-12-17T20:02:04+00:00

Signed-off-by: Ritesh Harjani 
Reviewed-by: Bart Van Assche 
Signed-off-by: Jens Axboe

Merge branch 'for-4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata

2016-12-13T21:26:24+00:00

Pull libata updates from Tejun Heo:

 - Adam added opt-in ATA command priority support.

 - There are machines which hide multiple nvme devices behind an ahci
   BAR. Dan Williams proposed a solution to force-switch the mode but
   deemed too hackishd. People are gonna discuss the proper way to
   handle the situation in nvme standard meetings. For now, detect and
   warn about the situation.

 - Low level driver specific changes.

Christoph Hellwig pipes in about the hidden nvme warning:
 "I wish that was the case. We've pretty much agreed that we'll want to
  implement it as a virtual PCIe root bridge, similar to Intels other
  'innovation' VMD that we work around that way.

  But Intel management has apparently decided that they don't want to
  spend more cycles on this now that Lenovo has an optional BIOS that
  doesn't force this broken mode anymore, and no one outside of Intel
  has enough information to implement something like this.

  So for now I guess this warning is it, until Intel reconsideres and
  spends resources on fixing up the damage their Chipset people caused"

* 'for-4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata:
  ahci: warn about remapped NVMe devices
  ahci-remap.h: add ahci remapping definitions
  nvme: move NVMe class code to pci_ids.h
  pata: imx: support controller modes up to PIO4
  pata: imx: add support of setting timings for PIO modes
  pata: imx: set controller PIO mode with .set_piomode callback
  pata: imx: sort headers out
  ata: set ncq_prio_enabled iff device has support
  ata: ATA Command Priority Disabled By Default
  ata: Enabling ATA Command Priorities
  block: Add iocontext priority to request
  ahci: qoriq: added ls1046a platform support

block: improve handling of the magic discard payload

2016-12-09T15:30:51+00:00

Instead of allocating a single unused biovec for discard requests, send
them down without any payload.  Instead we allow the driver to add a
"special" payload using a biovec embedded into struct request (unioned
over other fields never used while in the driver), and overloading
the number of segments for this case.

This has a couple of advantages:

 - we don't have to allocate the bio_vec
 - the amount of special casing for discard requests in the block
   layer is significantly reduced
 - using this same scheme for other request types is trivial,
   which will be important for implementing the new WRITE_ZEROES
   op on devices where it actually requires a payload (e.g. SCSI)
 - we can get rid of playing games with the request length, as
   we'll never touch it and completions will work just fine
 - it will allow us to support ranged discard operations in the
   future by merging non-contiguous discard bios into a single
   request
 - last but not least it removes a lot of code

This patch is the common base for my WIP series for ranges discards and to
remove discard_zeroes_data in favor of always using REQ_OP_WRITE_ZEROES,
so it would be good to get it in quickly.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Jens Axboe

block: add support for REQ_OP_WRITE_ZEROES

2016-12-01T14:58:40+00:00

This adds a new block layer operation to zero out a range of
LBAs. This allows to implement zeroing for devices that don't use
either discard with a predictable zero pattern or WRITE SAME of zeroes.
The prominent example of that is NVMe with the Write Zeroes command,
but in the future, this should also help with improving the way
zeroing discards work. For this operation, suitable entry is exported in
sysfs which indicate the number of maximum bytes allowed in one
write zeroes operation by the device.

Signed-off-by: Chaitanya Kulkarni 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Jens Axboe

block: add async variant of blkdev_issue_zeroout

2016-12-01T14:58:40+00:00

Similar to __blkdev_issue_discard this variant allows submitting
the final bio asynchronously and chaining multiple ranges
into a single completion.

Signed-off-by: Chaitanya Kulkarni 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Jens Axboe

block: Change extern inline to static inline

2016-11-18T14:44:23+00:00

With compilers which follow the C99 standard (like modern versions of
gcc and clang), "extern inline" does the opposite thing from older
versions of gcc (emits code for an externally linkable version of the
inline function).

"static inline" does the intended behavior in all cases instead.

Description taken from commit 6d91857d4826 ("staging, rtl8192e,
LLVMLinux: Change extern inline to static inline").

This also fixes the following GCC warning when building with CONFIG_PM
disabled:

  ./include/linux/blkdev.h:1143:20: warning: no previous prototype for 'blk_set_runtime_active' [-Wmissing-prototypes]

Fixes: d07ab6d11477 ("block: Add blk_set_runtime_active()")
Reviewed-by: Mika Westerberg 
Signed-off-by: Tobias Klauser 
Signed-off-by: Jens Axboe

blk-mq: make the polling code adaptive

2016-11-17T20:34:57+00:00

The previous commit introduced the hybrid sleep/poll mode. Take
that one step further, and use the completion latencies to
automatically sleep for half the mean completion time. This is
a good approximation.

This changes the 'io_poll_delay' sysfs file a bit to expose the
various options. Depending on the value, the polling code will
behave differently:

-1	Never enter hybrid sleep mode
 0	Use half of the completion mean for the sleep delay
>0	Use this specific value as the sleep delay

Signed-off-by: Jens Axboe 
Tested-By: Stephen Bates 
Reviewed-By: Stephen Bates

blk-mq: implement hybrid poll mode for sync O_DIRECT

2016-11-17T20:34:51+00:00

This patch enables a hybrid polling mode. Instead of polling after IO
submission, we can induce an artificial delay, and then poll after that.
For example, if the IO is presumed to complete in 8 usecs from now, we
can sleep for 4 usecs, wake up, and then do our polling. This still puts
a sleep/wakeup cycle in the IO path, but instead of the wakeup happening
after the IO has completed, it'll happen before. With this hybrid
scheme, we can achieve big latency reductions while still using the same
(or less) amount of CPU.

Signed-off-by: Jens Axboe 
Tested-By: Stephen Bates 
Reviewed-By: Stephen Bates

block: move poll code to blk-mq

2016-11-11T20:40:25+00:00

The poll code is blk-mq specific, let's move it to blk-mq.c. This
is a prep patch for improving the polling code.

Signed-off-by: Jens Axboe 
Reviewed-by: Christoph Hellwig

block: hook up writeback throttling

2016-11-10T20:53:40+00:00

Enable throttling of buffered writeback to make it a lot
more smooth, and has way less impact on other system activity.
Background writeback should be, by definition, background
activity. The fact that we flush huge bundles of it at the time
means that it potentially has heavy impacts on foreground workloads,
which isn't ideal. We can't easily limit the sizes of writes that
we do, since that would impact file system layout in the presence
of delayed allocation. So just throttle back buffered writeback,
unless someone is waiting for it.

The algorithm for when to throttle takes its inspiration in the
CoDel networking scheduling algorithm. Like CoDel, blk-wb monitors
the minimum latencies of requests over a window of time. In that
window of time, if the minimum latency of any request exceeds a
given target, then a scale count is incremented and the queue depth
is shrunk. The next monitoring window is shrunk accordingly. Unlike
CoDel, if we hit a window that exhibits good behavior, then we
simply increment the scale count and re-calculate the limits for that
scale value. This prevents us from oscillating between a
close-to-ideal value and max all the time, instead remaining in the
windows where we get good behavior.

Unlike CoDel, blk-wb allows the scale count to to negative. This
happens if we primarily have writes going on. Unlike positive
scale counts, this doesn't change the size of the monitoring window.
When the heavy writers finish, blk-bw quickly snaps back to it's
stable state of a zero scale count.

The patch registers a sysfs entry, 'wb_lat_usec'. This sets the latency
target to me met. It defaults to 2 msec for non-rotational storage, and
75 msec for rotational storage. Setting this value to '0' disables
blk-wb. Generally, a user would not have to touch this setting.

We don't enable WBT on devices that are managed with CFQ, and have
a non-root block cgroup attached. If we have a proportional share setup
on this particular disk, then the wbt throttling will interfere with
that. We don't have a strong need for wbt for that case, since we will
rely on CFQ doing that for us.

Signed-off-by: Jens Axboe