This adds a new module parameter to null_blk, blocking. If set, null_blk
will set the BLK_MQ_F_BLOCKING flag, indicating that it sometimes/always
needs to block in its ->queue_rq() function.  The intent is to help find
regressions in blocking drivers, since not many of them exist.

If null_blk is loaded with submit_queues > 1 and blocking=1, this
shows the regression recently fixed by bf4907c0.
Reviewed-by: NBart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Instead of keeping two levels of indirection for requests types, fold it
all into the operations.  The little caveat here is that previously
cmd_type only applied to struct request, while the request and bio op
fields were set to plain REQ_OP_READ/WRITE even for passthrough
operations.

Instead this patch adds new REQ_OP_* for SCSI passthrough and driver
private requests, althought it has to add two for each so that we
can communicate the data in/out nature of the request.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@fb.com>

When the lightnvm core had the "gennvm" layer between the device and the
target, there was a need for the core to be able to figure out which
target it should send an end_io callback to. Leading to a "double"
end_io, first for the media manager instance, and then for the target
instance. Now that core and gennvm is merged, there is no longer a need
for this, and a single end_io callback will do.
Signed-off-by: NMatias Bjørling <matias@cnexlabs.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

The number of configuration groups has been limited to one in current
code, even if there is support for up to four. With the introduction
of the open-channel SSD 1.3 specification, only a single
group is exposed onwards. Reflect this in the nvm_id structure.
Signed-off-by: NMatias Bjørling <matias@cnexlabs.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

ktime_set(S,N) was required for the timespec storage type and is still
useful for situations where a Seconds and Nanoseconds part of a time value
needs to be converted. For anything where the Seconds argument is 0, this
is pointless and can be replaced with a simple assignment.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>

If CONFIG_NVM is disabled, loading null_block module with use_lightnvm=1
fails. But there are no messages and documents related to the failure.

Add the appropriate error message.
Signed-off-by: NYasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>

Massaged the text a bit.
Signed-off-by: NJens Axboe <axboe@fb.com>

LightNVM compatible device drivers does not have a method to expose
LightNVM specific sysfs entries.

To enable LightNVM sysfs entries to be exposed, lightnvm device
drivers require a struct device to attach it to. To allow both the
actual device driver and lightnvm sysfs entries to coexist, the device
driver tracks the lifetime of the nvm_dev structure.

This patch refactors NVMe and null_blk to handle the lifetime of struct
nvm_dev, which eliminates the need for struct gendisk when a lightnvm
compatible device is provided.
Signed-off-by: NMatias Bjørling <m@bjorling.me>
Signed-off-by: NJens Axboe <axboe@fb.com>

With LightNVM enabled devices, the gendisk structure is not exposed
to the user. This hides the device driver specific sysfs entries, and
prevents binding of LightNVM geometry information to the device.

Refactor the device registration process, so that gendisk and
non-gendisk devices are easily managed.
Signed-off-by: NMatias Bjørling <m@bjorling.me>
Signed-off-by: NJens Axboe <axboe@fb.com>

All drivers use the default, so provide an inline version of it.  If we
ever need other queue mapping we can add an optional method back,
although supporting will also require major changes to the queue setup
code.

This provides better code generation, and better debugability as well.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NKeith Busch <keith.busch@intel.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

These two are confusing leftover of the old world order, combining
values of the REQ_OP_ and REQ_ namespaces.  For callers that don't
special case we mostly just replace bi_rw with bio_data_dir or
op_is_write, except for the few cases where a switch over the REQ_OP_
values makes more sense.  Any check for READA is replaced with an
explicit check for REQ_RAHEAD.  Also remove the READA alias for
REQ_RAHEAD.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NMike Christie <mchristi@redhat.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

After register null_blk devices into lightnvm, we forget
to add these devices to the the nullb_list, makes them
invisible to the null_blk driver.
Signed-off-by: NWenwei Tao <ww.tao0320@gmail.com>
Fixes: a514379b ("null_blk: oops when initializing without lightnvm")
Signed-off-by: NJens Axboe <axboe@fb.com>

If the LightNVM subsystem is not compiled into the kernel, and the
null_blk device driver requests lightnvm to be initialized. The call to
nvm_register fails and the null_add_dev function cleans up the
initialization. However, at this point the null block device has
already been added to the nullb_list and thus a second cleanup will
occur when the function has returned, that leads to a double call to
blk_cleanup_queue.
Signed-off-by: NMatias Bjørling <m@bjorling.me>
Signed-off-by: NJens Axboe <axboe@fb.com>

System block allows the device to initialize with its configured media
manager. The system blocks is written to disk, and read again when media
manager is determined. For this to work, the backend must store the
data. Device drivers, such as null_blk, does not have any backend
storage. This patch allows the media manager to be initialized without a
storage backend.

It also fix incorrect configuration of capabilities in null_blk, as it
does not support get/set bad block interface.
Signed-off-by: NMatias Bjørling <m@bjorling.me>
Signed-off-by: NJens Axboe <axboe@fb.com>

Dividing a sector_t number should be done using sector_div rather than do_div
to optimize the 32-bit sector_t case, and with the latest do_div optimizations,
we now get a compile-time warning for this:

arch/arm/include/asm/div64.h:32:95: note: expected 'uint64_t * {aka long long unsigned int *}' but argument is of type 'sector_t * {aka long unsigned int *}'
drivers/block/null_blk.c:521:81: warning: comparison of distinct pointer types lacks a cast

This changes the newly added code to use sector_div. It is a simplified version
of the original patch, as Linus Torvalds pointed out that we should not be using
an expensive division function in the first place.

This version was suggested by Matias Bjorling.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Cc: Matias Bjorling <m@bjorling.me>
Fixes: b2b7e001 ("null_blk: register as a LightNVM device")
Signed-off-by: NJens Axboe <axboe@fb.com>

To implement sync I/O support within the LightNVM core, the end_io
functions are refactored to take an end_io function pointer instead of
testing for initialized media manager, followed by calling its end_io
function.

Sync I/O can then be implemented using a callback that signal I/O
completion. This is similar to the logic found in blk_to_execute_io().
By implementing it this way, the underlying device I/Os submission logic
is abstracted away from core, targets, and media managers.
Signed-off-by: NMatias Bjørling <m@bjorling.me>
Signed-off-by: NJens Axboe <axboe@fb.com>

If null_blk is run in NULL_IRQ_TIMER mode and with queue_mode NULL_Q_RQ,
we need to restart the queue from the hrtimer interrupt. We can't
directly invoke the request_fn from that context, so punt the queue run
to async kblockd context.
Tested-by: NRabin Vincent <rabin@rab.in>
Signed-off-by: NJens Axboe <axboe@fb.com>

blk_end_request_all may free request, so we need to save
request_queue pointer before blk_end_request_all call.

The problem was introduced in commit cf8ecc5a
("null_blk: guarantee device restart in all irq modes")
and causes general protection fault with slab poisoning
enabled.

Fixes: cf8ecc5a ("null_blk: guarantee device
       restart in all irq modes")
Signed-off-by: NMike Krinkin <krinkin.m.u@gmail.com>
Reviewed-by: NMing Lei <tom.leiming@gmail.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Module couldn't release resource properly during the initialization. To
fix this issue, we will clean up the proper resource before returning.
Signed-off-by: NMinfei Huang <mnfhuang@gmail.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

In the case where a request queue is passed to the low lever lightnvm
device drive integration, the device driver might pass its admin
commands through another queue. Instead pass nvm_dev, and let the
low level drive the appropriate queue.
Reported-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NMatias Bjørling <m@bjorling.me>
Signed-off-by: NJens Axboe <axboe@fb.com>

We already have the reserved flag, and a nowait flag awkwardly encoded as
a gfp_t.  Add a real flags argument to make the scheme more extensible and
allow for a nicer calling convention.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@fb.com>

This commit at least doubles the maximum value for
completion_nsec. This helps in special cases where one wants/needs to
emulate an extremely slow I/O (for example to spot bugs).
Signed-off-by: NPaolo Valente <paolo.valente@unimore.it>
Signed-off-by: NArianna Avanzini <avanzini@google.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

In single-queue (block layer) mode,the function null_rq_prep_fn stops
the device if alloc_cmd fails. Then, once stopped, the device must be
restarted on the next command completion, so that the request(s) for
which alloc_cmd failed can be requeued. Otherwise the device hangs.

Unfortunately, device restart is currently performed only for delayed
completions, i.e., in irqmode==2. This fact causes hangs, for the
above reasons, with the other irqmodes in combination with single-queue
block layer.

This commits addresses this issue by making sure that, if stopped, the
device is properly restarted for all irqmodes on completions.
Signed-off-by: NPaolo Valente <paolo.valente@unimore.it>
Signed-off-by: NArianna AVanzini <avanzini@google.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

For the Timer IRQ mode (i.e., when command completions are delayed),
there is one timer for each CPU. Each of these timers
. has a completion queue associated with it, containing all the
  command completions to be executed when the timer fires;
. is set, and a new completion-to-execute is inserted into its
  completion queue, every time the dispatch code for a new command
  happens to be executed on the CPU related to the timer.

This implies that, if the dispatch of a new command happens to be
executed on a CPU whose timer has already been set, but has not yet
fired, then the timer is set again, to the completion time of the
newly arrived command. When the timer eventually fires, all its queued
completions are executed.

This way of handling delayed command completions entails the following
problem: if more than one command completion is inserted into the
queue of a timer before the timer fires, then the expiration time for
the timer is moved forward every time each of these completions is
enqueued. As a consequence, only the last completion enqueued enjoys a
correct execution time, while all previous completions are unjustly
delayed until the last completion is executed (and at that time they
are executed all together).

Specifically, if all the above completions are enqueued almost at the
same time, then the problem is negligible. On the opposite end, if
every completion is enqueued a while after the previous completion was
enqueued (in the extreme case, it is enqueued only right before the
timer would have expired), then every enqueued completion, except for
the last one, experiences an inflated delay, proportional to the number
of completions enqueued after it. In the end, commands, and thus I/O
requests, may be completed at an arbitrarily lower rate than the
desired one.

This commit addresses this issue by replacing per-CPU timers with
per-command timers, i.e., by associating an individual timer with each
command.
Signed-off-by: NPaolo Valente <paolo.valente@unimore.it>
Signed-off-by: NArianna Avanzini <avanzini@google.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

The gendisk structure has not been initialized when using lightnvm.
Make sure to not delete it upon exit. Also make sure that we use the
appropriate disk_name at unregistration.
Signed-off-by: NMatias Bjørling <m@bjorling.me>
Signed-off-by: NJens Axboe <axboe@fb.com>

The linear addressing mode was removed in 7386af27. Make null_blk instead
expose the ppa format geometry and support the generic addressing mode.
Signed-off-by: NMatias Bjørling <m@bjorling.me>
Signed-off-by: NJens Axboe <axboe@fb.com>

Instead of using a page pool, we can save memory by only allocating room
for 64 entries for the ppa command. Introduce a ppa_cache to allocate only
the required memory for the ppa list.
Signed-off-by: NMatias Bjørling <m@bjorling.me>
Signed-off-by: NJens Axboe <axboe@fb.com>

Add support for registering as a LightNVM device. This allows us to
evaluate the performance of the LightNVM subsystem.

In /drivers/Makefile, LightNVM is moved above block device drivers
to make sure that the LightNVM media managers have been initialized
before drivers under /drivers/block are initialized.
Signed-off-by: NMatias Bjørling <m@bjorling.me>
Fix by Jens Axboe to remove unneeded slab cache and the following
memory leak.
Signed-off-by: NJens Axboe <axboe@fb.com>

No functional changes in this patch, but it prepares us for returning
a more useful cookie related to the IO that was queued up.
Signed-off-by: NJens Axboe <axboe@fb.com>
Acked-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NKeith Busch <keith.busch@intel.com>

blk_mq_complete_request may be a no-op if the request has already
been completed by others means (e.g. a timeout or cancellation), but
currently drivers have to set rq->errors before calling
blk_mq_complete_request, which might leave us with the wrong error value.

Add an error parameter to blk_mq_complete_request so that we can
defer setting rq->errors until we known we won the race to complete the
request.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NSagi Grimberg <sagig@mellanox.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

set_capacity() sets device's capacity using 512 bytes sectors.
null_blk calculates the number of sectors by size / bs, which
set_capacity is called with. This led to null_blk exposing the
wrong number of sectors when bs is not 512 bytes.
Signed-off-by: NMatias Bjørling <m@bjorling.me>
Reviewed-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Driver was not freeing the memory allocated for internal nullb queues.
This patch frees the memory during driver unload.
Signed-off-by: NMatias Bjørling <mb@lightnvm.io>
Signed-off-by: NJens Axboe <axboe@fb.com>

Currently we have two different ways to signal an I/O error on a BIO:

 (1) by clearing the BIO_UPTODATE flag
 (2) by returning a Linux errno value to the bi_end_io callback

The first one has the drawback of only communicating a single possible
error (-EIO), and the second one has the drawback of not beeing persistent
when bios are queued up, and are not passed along from child to parent
bio in the ever more popular chaining scenario.  Having both mechanisms
available has the additional drawback of utterly confusing driver authors
and introducing bugs where various I/O submitters only deal with one of
them, and the others have to add boilerplate code to deal with both kinds
of error returns.

So add a new bi_error field to store an errno value directly in struct
bio and remove the existing mechanisms to clean all this up.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinecke <hare@suse.de>
Reviewed-by: NNeilBrown <neilb@suse.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

end_cmd finishes request associated with nullb_cmd struct, so we
should save pointer to request_queue in a local variable before
calling end_cmd.

The problem was causes general protection fault with slab poisoning
enabled.

Fixes: 8b70f45e ("null_blk: restart request processing on completion handler")
Tested-by: NAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: NMike Krinkin <krinkin.m.u@gmail.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

When irqmode=2 (IRQ completion handler is timer) and queue_mode=1
(Block interface to use is rq), the completion handler should restart
request handling for any pending requests on a queue because request
processing stops when the number of commands are queued more than
hw_queue_depth (null_rq_prep_fn returns BLKPREP_DEFER).

Without this change, the following command cannot finish.

	# modprobe null_blk irqmode=2 queue_mode=1 hw_queue_depth=1
	# fio --name=t --rw=read --size=1g --direct=1 \
	  --ioengine=libaio --iodepth=64 --filename=/dev/nullb0
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Cc: Jens Axboe <axboe@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

When irqmode=2 (IRQ completion handler is timer), timer handler should
be called on the same CPU where the timer has been started.

Since completion_queues are per-cpu and the completion handler only
touches completion_queue for local CPU, we need to prevent the handler
from running on a different CPU where the timer has been started.
Otherwise, the IO cannot be completed until another completion handler
is executed on that CPU.
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Cc: Jens Axboe <axboe@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Most code already uses consts for the struct kernel_param_ops,
sweep the kernel for the last offending stragglers. Other than
include/linux/moduleparam.h and kernel/params.c all other changes
were generated with the following Coccinelle SmPL patch. Merge
conflicts between trees can be handled with Coccinelle.

In the future git could get Coccinelle merge support to deal with
patch --> fail --> grammar --> Coccinelle --> new patch conflicts
automatically for us on patches where the grammar is available and
the patch is of high confidence. Consider this a feature request.

Test compiled on x86_64 against:

	* allnoconfig
	* allmodconfig
	* allyesconfig

@ const_found @
identifier ops;
@@

const struct kernel_param_ops ops = {
};

@ const_not_found depends on !const_found @
identifier ops;
@@

-struct kernel_param_ops ops = {
+const struct kernel_param_ops ops = {
};

Generated-by: Coccinelle SmPL
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Junio C Hamano <gitster@pobox.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: cocci@systeme.lip6.fr
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NLuis R. Rodriguez <mcgrof@suse.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

null_blk is partitionable, but it doesn't store any of the info. When
it is loaded, you would normally see:

[1226739.343608]  nullb0: unknown partition table
[1226739.343746]  nullb1: unknown partition table

which can confuse some people. Add the appropriate gendisk flag
to suppress this info.
Signed-off-by: NJens Axboe <axboe@fb.com>

Check IS_ERR_OR_NULL(return value) instead of just return value.
Signed-off-by: NMing Lei <ming.lei@canonical.com>

Reduced to IS_ERR() by me, we never return NULL.
Signed-off-by: NJens Axboe <axboe@fb.com>

When either queue_mode or irq_mode parameter is set outside its
boundaries, the driver will not complete requests. This stalls driver
initialization when partitions are probed. Fix by setting out of bound
values to the parameters default.
Signed-off-by: NMatias Bjørling <m@bjorling.me>

Updated by me to have the parse+check in just one function.
Signed-off-by: NJens Axboe <axboe@fb.com>

Since we have the notion of a 'last' request in a chain, we can use
this to have the hardware optimize the issuing of requests. Add
a list_head parameter to queue_rq that the driver can use to
temporarily store hw commands for issue when 'last' is true. If we
are doing a chain of requests, pass in a NULL list for the first
request to force issue of that immediately, then batch the remainder
for deferred issue until the last request has been sent.

Instead of adding yet another argument to the hot ->queue_rq path,
encapsulate the passed arguments in a blk_mq_queue_data structure.
This is passed as a constant, and has been tested as faster than
passing 4 (or even 3) args through ->queue_rq. Update drivers for
the new ->queue_rq() prototype. There are no functional changes
in this patch for drivers - if they don't use the passed in list,
then they will just queue requests individually like before.
Signed-off-by: NJens Axboe <axboe@fb.com>