To maximise responsiveness, BFQ raises the weight, and performs device
idling, for bfq_queues associated with processes deemed as
interactive. In particular, weight raising has a maximum duration,
equal to the time needed to start a large application. If a
weight-raised process goes on doing I/O beyond this maximum duration,
it loses weight-raising.

This mechanism is evidently vulnerable to the following false
positives: I/O-bound applications that will go on doing I/O for much
longer than the duration of weight-raising. These applications have
basically no benefit from being weight-raised at the beginning of
their I/O. On the opposite end, while being weight-raised, these
applications
a) unjustly steal throughput to applications that may truly need
low latency;
b) make BFQ uselessly perform device idling; device idling results
in loss of device throughput with most flash-based storage, and may
increase latencies when used purposelessly.

This commit adds a countermeasure to reduce both the above
problems. To introduce this countermeasure, we provide the following
extra piece of information (full details in the comments added by this
commit). During the start-up of the large application used as a
reference to set the duration of weight-raising, involved processes
transfer at most ~110K sectors each. Accordingly, a process initially
deemed as interactive has no right to be weight-raised any longer,
once transferred 110K sectors or more.

Basing on this consideration, this commit early-ends weight-raising
for a bfq_queue if the latter happens to have received an amount of
service at least equal to 110K sectors (actually, a little bit more,
to keep a safety margin). I/O-bound applications that reach a high
throughput, such as file copy, get to this threshold much before the
allowed weight-raising period finishes. Thus this early ending of
weight-raising reduces the amount of time during which these
applications cause the problems described above.
Tested-by: NOleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: NHolger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: NPaolo Valente <paolo.valente@linaro.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Asynchronous I/O can easily starve synchronous I/O (both sync reads
and sync writes), by consuming all request tags. Similarly, storms of
synchronous writes, such as those that sync(2) may trigger, can starve
synchronous reads. In their turn, these two problems may also cause
BFQ to loose control on latency for interactive and soft real-time
applications. For example, on a PLEXTOR PX-256M5S SSD, LibreOffice
Writer takes 0.6 seconds to start if the device is idle, but it takes
more than 45 seconds (!) if there are sequential writes in the
background.

This commit addresses this issue by limiting the maximum percentage of
tags that asynchronous I/O requests and synchronous write requests can
consume. In particular, this commit grants a higher threshold to
synchronous writes, to prevent the latter from being starved by
asynchronous I/O.

According to the above test, LibreOffice Writer now starts in about
1.2 seconds on average, regardless of the background workload, and
apart from some rare outlier. To check this improvement, run, e.g.,
sudo ./comm_startup_lat.sh bfq 5 5 seq 10 "lowriter --terminate_after_init"
for the comm_startup_lat benchmark in the S suite [1].

[1] https://github.com/Algodev-github/STested-by: NOleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: NHolger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: NPaolo Valente <paolo.valente@linaro.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

If we run into blk_mq_request_direct_issue(), when queue is busy, we
don't want to dispatch this request into hctx->dispatch_list, and
what we need to do is to return the queue busy info to caller, so
that caller can deal with it well.

Fixes: 396eaf21 ("blk-mq: improve DM's blk-mq IO merging via blk_insert_cloned_request feedback")
Reported-by: NLaurence Oberman <loberman@redhat.com>
Reviewed-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Fixes: 4246a0b6 ("block: add a bi_error field to struct bio")
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

After commit:

923218f6 ("blk-mq: don't allocate driver tag upfront for flush rq")

we no longer use the 'can_block' argument in
blk_mq_sched_insert_request(). Kill it.
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

Added actual commit message as to why it's being removed.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

blk_insert_cloned_request() is called in the fast path of a dm-rq driver
(e.g. blk-mq request-based DM mpath).  blk_insert_cloned_request() uses
blk_mq_request_bypass_insert() to directly append the request to the
blk-mq hctx->dispatch_list of the underlying queue.

1) This way isn't efficient enough because the hctx spinlock is always
used.

2) With blk_insert_cloned_request(), we completely bypass underlying
queue's elevator and depend on the upper-level dm-rq driver's elevator
to schedule IO.  But dm-rq currently can't get the underlying queue's
dispatch feedback at all.  Without knowing whether a request was issued
or not (e.g. due to underlying queue being busy) the dm-rq elevator will
not be able to provide effective IO merging (as a side-effect of dm-rq
currently blindly destaging a request from its elevator only to requeue
it after a delay, which kills any opportunity for merging).  This
obviously causes very bad sequential IO performance.

Fix this by updating blk_insert_cloned_request() to use
blk_mq_request_direct_issue().  blk_mq_request_direct_issue() allows a
request to be issued directly to the underlying queue and returns the
dispatch feedback (blk_status_t).  If blk_mq_request_direct_issue()
returns BLK_SYS_RESOURCE the dm-rq driver will now use DM_MAPIO_REQUEUE
to _not_ destage the request.  Whereby preserving the opportunity to
merge IO.

With this, request-based DM's blk-mq sequential IO performance is vastly
improved (as much as 3X in mpath/virtio-scsi testing).
Signed-off-by: NMing Lei <ming.lei@redhat.com>
[blk-mq.c changes heavily influenced by Ming Lei's initial solution, but
they were refactored to make them less fragile and easier to read/review]
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

No functional change.  Just makes code flow more logically.

In following commit, __blk_mq_try_issue_directly() will be used to
return the dispatch result (blk_status_t) to DM.  DM needs this
information to improve IO merging.
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We know this WARN_ON is harmless and in reality it may be trigged,
so convert it to printk() and dump_stack() to avoid to confusing
people.

Also add comment about two releated races here.

Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Stefan Haberland <sth@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "jianchao.wang" <jianchao.w.wang@oracle.com>
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

When hctx->next_cpu is set from possible online CPUs, there is one
race in which hctx->next_cpu may be set as >= nr_cpu_ids, and finally
break workqueue.

The race can be triggered in the following two sitations:

1) when one CPU is becoming DEAD, blk_mq_hctx_notify_dead() is called
to dispatch requests from the DEAD cpu context, but at that
time, this DEAD CPU has been cleared from 'cpu_online_mask', so all
CPUs in hctx->cpumask may become offline, and cause hctx->next_cpu set
a bad value.

2) blk_mq_delay_run_hw_queue() is called from CPU B, and found the queue
should be run on the other CPU A, then CPU A may become offline at the
same time and all CPUs in hctx->cpumask become offline.

This patch deals with this issue by re-selecting next CPU, and making
sure it is set correctly.

Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Stefan Haberland <sth@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Reported-by: N"jianchao.wang" <jianchao.w.wang@oracle.com>
Tested-by: N"jianchao.wang" <jianchao.w.wang@oracle.com>
Fixes: 20e4d813 ("blk-mq: simplify queue mapping & schedule with each possisble CPU")
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

'struct frame' uses two variables to store the sent timestamp - 'struct
timeval' and jiffies. jiffies is used to avoid discrepancies caused by
updates to system time. 'struct timeval' is deprecated because it uses
32-bit representation for seconds which will overflow in year 2038.

This patch does the following:
- Replace the use of 'struct timeval' and jiffies with ktime_t, which
  is the recommended type for timestamping
- ktime_t provides both long range (like jiffies) and high resolution
  (like timeval). Using ktime_get (monotonic time) instead of wall-clock
  time prevents any discprepancies caused by updates to system time.

[updates by Arnd below]
The original patch from Tina never went anywhere as we discussed how
to keep the impact on performance minimal. I've started over now but
arrived at basically the same patch that she had originally, except for
an slightly improved tsince_hr() function. I'm making it more robust
against overflows, and also optimize explicitly for the common case
in which a frame is less than 4.2 seconds old, using only a 32-bit
division in that case.

This should make the new version more efficient than the old code,
since we replace the existing two 32-bit division in do_gettimeofday()
plus one multiplication with a single single 32-bit division in
tsince_hr() and drop the double bookkeeping. It's also more efficient
than the ktime_get_us() API we discussed before, since that would
also rely on multiple divisions.

Link: https://lists.linaro.org/pipermail/y2038/2015-May/000276.htmlSigned-off-by: NTina Ruchandani <ruchandani.tina@gmail.com>
Cc: Ed Cashin <ed.cashin@acm.org>
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Some older compilers (gcc-4.4 through 4.6 in particular) struggle
with the way that blkg_rwstat_read() returns a structure, leading
to excessive stack usage and rather inefficient code:

block/blk-cgroup.c: In function 'blkg_destroy':
block/blk-cgroup.c:354:1: error: the frame size of 1296 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]
block/cfq-iosched.c: In function 'cfqg_stats_add_aux':
block/cfq-iosched.c:753:1: error: the frame size of 1928 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]
block/bfq-cgroup.c: In function 'bfqg_stats_add_aux':
block/bfq-cgroup.c:299:1: error: the frame size of 1928 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]

I also notice that there is no point in using atomic accesses
for the local variables, so storing the temporaries in simple 'u64'
variables not only avoids the stack usage on older compilers but
also improves the object code on modern versions.

Fixes: e6269c44 ("blkcg: add blkg_[rw]stat->aux_cnt and replace cfq_group->dead_stats with it")
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

DM is no longer prone to having its request_queue be improperly
initialized.

Summary of changes:

- defer DM's blk_register_queue() from add_disk()-time until
  dm_setup_md_queue() by using add_disk_no_queue_reg() in alloc_dev().

- dm_setup_md_queue() is updated to fully initialize DM's request_queue
  (_after_ all table loads have occurred and the request_queue's type,
  features and limits are known).

A very welcome side-effect of these changes is DM no longer needs to:
1) backfill the "mq" sysfs entry (because historically DM didn't
initialize the request_queue to use blk-mq until _after_
blk_register_queue() was called via add_disk()).
2) call elv_register_queue() to get .request_fn request-based DM
device's "iosched" exposed in syfs.

In addition, blk-mq debugfs support is now made available because
request-based DM's blk-mq request_queue is now properly initialized
before dm_setup_md_queue() calls blk_register_queue().

These changes also stave off the need to introduce new DM-specific
workarounds in block core, e.g. this proposal:
https://patchwork.kernel.org/patch/10067961/

In the end DM devices should be less unicorn in nature (relative to
initialization and availability of block core infrastructure provided by
the request_queue).
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Tested-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

During stress tests by syzkaller on the sg driver the block layer
infrequently returns EINVAL. Closer inspection shows the block
layer was trying to return ENOMEM (which is much more
understandable) but for some reason overroad that useful error.

Patch below does not show this (unchanged) line:
   ret =__blk_rq_map_user_iov(rq, map_data, &i, gfp_mask, copy);
That 'ret' was being overridden when that function failed.
Signed-off-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Since I can remember DM has forced the block layer to allow the
allocation and initialization of the request_queue to be distinct
operations.  Reason for this is block/genhd.c:add_disk() has requires
that the request_queue (and associated bdi) be tied to the gendisk
before add_disk() is called -- because add_disk() also deals with
exposing the request_queue via blk_register_queue().

DM's dynamic creation of arbitrary device types (and associated
request_queue types) requires the DM device's gendisk be available so
that DM table loads can establish a master/slave relationship with
subordinate devices that are referenced by loaded DM tables -- using
bd_link_disk_holder().  But until these DM tables, and their associated
subordinate devices, are known DM cannot know what type of request_queue
it needs -- nor what its queue_limits should be.

This chicken and egg scenario has created all manner of problems for DM
and, at times, the block layer.

Summary of changes:

- Add device_add_disk_no_queue_reg() and add_disk_no_queue_reg() variant
  that drivers may use to add a disk without also calling
  blk_register_queue().  Driver must call blk_register_queue() once its
  request_queue is fully initialized.

- Return early from blk_unregister_queue() if QUEUE_FLAG_REGISTERED
  is not set.  It won't be set if driver used add_disk_no_queue_reg()
  but driver encounters an error and must del_gendisk() before calling
  blk_register_queue().

- Export blk_register_queue().

These changes allow DM to use add_disk_no_queue_reg() to anchor its
gendisk as the "master" for master/slave relationships DM must establish
with subordinate devices referenced in DM tables that get loaded.  Once
all "slave" devices for a DM device are known its request_queue can be
properly initialized and then advertised via sysfs -- important
improvement being that no request_queue resource initialization
performed by blk_register_queue() is missed for DM devices anymore.
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

The original commit e9a823fb (block: fix warning when I/O elevator
is changed as request_queue is being removed) is pretty conflated.
"conflated" because the resource being protected by q->sysfs_lock isn't
the queue_flags (it is the 'queue' kobj).

q->sysfs_lock serializes __elevator_change() (via elv_iosched_store)
from racing with blk_unregister_queue():
1) By holding q->sysfs_lock first, __elevator_change() can complete
before a racing blk_unregister_queue().
2) Conversely, __elevator_change() is testing for QUEUE_FLAG_REGISTERED
in case elv_iosched_store() loses the race with blk_unregister_queue(),
it needs a way to know the 'queue' kobj isn't there.

Expand the scope of blk_unregister_queue()'s q->sysfs_lock use so it is
held until after the 'queue' kobj is removed.

To do so blk_mq_unregister_dev() must not also take q->sysfs_lock.  So
rename __blk_mq_unregister_dev() to blk_mq_unregister_dev().

Also, blk_unregister_queue() should use q->queue_lock to protect against
any concurrent writes to q->queue_flags -- even though chances are the
queue is being cleaned up so no concurrent writes are likely.

Fixes: e9a823fb ("block: fix warning when I/O elevator is changed as request_queue is being removed")
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

device_add_disk() will only call bdi_register_owner() if
!GENHD_FL_HIDDEN, so it follows that del_gendisk() should only call
bdi_unregister() if !GENHD_FL_HIDDEN.

Found with code inspection.  bdi_unregister() won't do any harm if
bdi_register_owner() wasn't used but best to avoid the unnecessary
call to bdi_unregister().

Fixes: 8ddcd653 ("block: introduce GENHD_FL_HIDDEN")
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

A previous commit moved the clearing of rq->rq_flags later,
but we may have already set RQF_MQ_INFLIGHT when that happens.
Ensure that we correctly initialize rq->rq_flags to the
right value.

This is based on an original fix by Ming, just rewritten to not
require a conditional.

Fixes: 7c3fb70f ("block: rearrange a few request fields for better cache layout")
Reviewed-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Looking at debug output, we see:

./000000009ddfa913/requeue_list:000000009646711c {.op=READ, .state=idle, gen=0x1
18, abort_gen=0x0, .cmd_flags=, .rq_flags=SORTED|1|SOFTBARRIER|IO_STAT, complete
=0, .tag=-1, .internal_tag=217}

Note the '1' between SORTED and SOFTBARRIER - that's because no name
as defined for RQF_STARTED. Fixed that.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

The previous patch assigns interrupt vectors to all possible CPUs, so
now hctx can be mapped to possible CPUs, this patch applies this fact
to simplify queue mapping & schedule so that we don't need to handle
CPU hotplug for dealing with physical CPU plug & unplug. With this
simplication, we can work well on physical CPU plug & unplug, which
is a normal use case for VM at least.

Make sure we allocate blk_mq_ctx structures for all possible CPUs, and
set hctx->numa_node for possible CPUs which are mapped to this hctx. And
only choose the online CPUs for schedule.
Reported-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Tested-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Tested-by: NStefan Haberland <sth@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Fixes: 4b855ad3 ("blk-mq: Create hctx for each present CPU")
(merged the three into one because any single one may not work, and fix
selecting online CPUs for scheduler)
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Currently we assign managed interrupt vectors to all present CPUs.  This
works fine for systems were we only online/offline CPUs.  But in case of
systems that support physical CPU hotplug (or the virtualized version of
it) this means the additional CPUs covered for in the ACPI tables or on
the command line are not catered for.  To fix this we'd either need to
introduce new hotplug CPU states just for this case, or we can start
assining vectors to possible but not present CPUs.
Reported-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Tested-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Tested-by: NStefan Haberland <sth@linux.vnet.ibm.com>
Fixes: 4b855ad3 ("blk-mq: Create hctx for each present CPU")
Cc: linux-kernel@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This patch does not change any functionality but makes the
blk_mq_mark_tag_wait() code slightly easier to read.
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Selecting FAULT_INJECTION causes a Kconfig warning when CONFIG_DEBUG_KERNEL
is not set:

warning: (BLK_DEV_NULL_BLK && DRM_I915_SELFTEST) selects FAULT_INJECTION which has unmet direct dependencies (DEBUG_KERNEL)

The other drivers that use FAULT_INJECTION tend to have a separate
Kconfig symbol for turning on that feature, so let's do the same
thing here. This may add a bit more complexity than we like, but
it avoids the warning and is more consistent with the rest of the
kernel.

Fixes: 93b57046 ("null_blk: add option for managing IO timeouts")
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This patch avoids that sparse reports the following:

block/blk-mq.c:637:33: warning: context imbalance in 'hctx_unlock' - unexpected unlock
block/blk-mq.c:642:9: warning: context imbalance in 'hctx_lock' - wrong count at exit
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

After the first few months, the message has not led to many bug reports.
It's been almost five years now, and in practice the main source of
it seems to be MTIOCGET that someone is using to detect tape devices.
While we could whitelist it just like CDROM_GET_CAPABILITY, this patch
just removes the message altogether.

The patch also removes the "safe but not very useful" ioctl whitelist,
as suggested by Christoph.  I doubt anything is using most of those
ioctls _in general_, let alone on a partition.
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Move completion related items (like the call single data) near the
end of the struct, instead of mixing them in with the initial
queueing related fields.

Move queuelist below the bio structures. Then we have all
queueing related bits in the first cache line.

This yields a 1.5-2% increase in IOPS for a null_blk test, both for
sync and for high thread count access. Sync test goes form 975K to
992K, 32-thread case from 20.8M to 21.2M IOPS.
Reviewed-by: NBart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We only have one atomic flag left. Instead of using an entire
unsigned long for that, steal the bottom bit of the deadline
field that we already reserved.

Remove ->atomic_flags, since it's now unused.
Reviewed-by: NBart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We reduce the resolution of request expiry, but since we're already
using jiffies for this where resolution depends on the kernel
configuration and since the timeout resolution is coarse anyway,
that should be fine.
Reviewed-by: NBart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We don't need this to be an atomic flag, it can be a regular
flag. We either end up on the same CPU for the polling, in which
case the state is sane, or we did the sleep which would imply
the needed barrier to ensure we see the right state.
Reviewed-by: NBart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We are missing ZONE_WRITE_LOCKED and MQ_TIMEOUT_EXPIRED, add them
so the debugfs bits can decode them.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Uses common code for determining if an error should be retried on
alternate path.
Acked-by: NMike Snitzer <snitzer@redhat.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NKeith Busch <keith.busch@intel.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Uses common code for determining if an error should be retried on
alternate path.
Acked-by: NMike Snitzer <snitzer@redhat.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NKeith Busch <keith.busch@intel.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This patch provides a common decoder for block status path related errors
that may be retried so various entities wishing to consult this do not
have to duplicate this decision.
Acked-by: NMike Snitzer <snitzer@redhat.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NKeith Busch <keith.busch@intel.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This removes nvme multipath's specific status decoding to see if failover
is needed, using the generic blk_status_t that was decoded earlier. This
abstraction from the raw NVMe status means all status decoding exists
in one place.
Acked-by: NMike Snitzer <snitzer@redhat.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NKeith Busch <keith.busch@intel.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This adds more NVMe status code translations to blk_status_t values,
and captures all the current status codes NVMe multipath uses.
Acked-by: NMike Snitzer <snitzer@redhat.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NKeith Busch <keith.busch@intel.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

It is nontrivial to derive from the blk-mq source code when
blk_mq_tags.active_queues is decremented. Hence add a comment that
explains this.
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

UFS partitions from newer versions of FreeBSD 10 and 11 use relative
addressing for their subpartitions. But older versions of FreeBSD still
use absolute addressing just like OpenBSD and NetBSD.

Instead of simply testing for a FreeBSD partition, the code needs to
also test if the starting offset of the C subpartition is zero.

https://bugzilla.kernel.org/show_bug.cgi?id=197733Signed-off-by: NRichard Narron <comet.berkeley@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Use the fault injection framework to provide a way for null_blk
to configure timeouts. This only works for queue_mode 1 and 2,
since the bio mode doesn't have code for tracking timeouts.

Let's say you want to have a 10% chance of timing out every
100,000 requests, and for 5 total timeouts, you could do:

modprobe null_blk timeout="100000,10,0,5"

This is useful for adding blktests to test that IO timeouts
are handled appropriately.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Commit '7b9e9361' ("blk-mq-sched: unify request finished methods")
changed the old name of current bfq_finish_request method, but left it
unchanged elsewhere in the code (related comments, part of function
name bfq_put_rq_priv_body).

This commit fixes all occurrences of the old name of this method by
changing them into the current name.

Fixes: 7b9e9361 ("blk-mq-sched: unify request finished methods")
Reviewed-by: NPaolo Valente <paolo.valente@linaro.org>
Signed-off-by: NFederico Motta <federico@willer.it>
Signed-off-by: NChiara Bruschi <bruschi.chiara@outlook.it>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This reverts commit a2d37968.

If max segment size isn't 512-aligned, this patch won't work well.

Also once multipage bvec is enabled, adjacent bvecs won't be physically
contiguous if page is added via bio_add_page(), so we don't need this
kind of complicated logic.
Reported-by: NDmitry Osipenko <digetx@gmail.com>
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This is needed to ensure that we actually handle timeouts.
Without it, the queue_mode=1 path will never call blk_add_timer(),
and the queue_mode=2 path will continually just return
EH_RESET_TIMER and we never actually complete the offending request.

This was used to test the new timeout code, and the changes around
killing off REQ_ATOM_COMPLETE.
Signed-off-by: NJens Axboe <axboe@kernel.dk>