This is due to  commit 86839c56
"xen/block: add multi-page ring support"

When using an guest under UEFI - after the domain is destroyed
the following warning comes from blkback.

------------[ cut here ]------------
WARNING: CPU: 2 PID: 95 at
/home/julien/works/linux/drivers/block/xen-blkback/xenbus.c:274
xen_blkif_deferred_free+0x1f4/0x1f8()
Modules linked in:
CPU: 2 PID: 95 Comm: kworker/2:1 Tainted: G        W       4.2.0 #85
Hardware name: APM X-Gene Mustang board (DT)
Workqueue: events xen_blkif_deferred_free
Call trace:
[<ffff8000000890a8>] dump_backtrace+0x0/0x124
[<ffff8000000891dc>] show_stack+0x10/0x1c
[<ffff8000007653bc>] dump_stack+0x78/0x98
[<ffff800000097e88>] warn_slowpath_common+0x9c/0xd4
[<ffff800000097f80>] warn_slowpath_null+0x14/0x20
[<ffff800000557a0c>] xen_blkif_deferred_free+0x1f0/0x1f8
[<ffff8000000ad020>] process_one_work+0x160/0x3b4
[<ffff8000000ad3b4>] worker_thread+0x140/0x494
[<ffff8000000b2e34>] kthread+0xd8/0xf0
---[ end trace 6f859b7883c88cdd ]---

Request allocation has been moved to connect_ring, which is called every
time blkback connects to the frontend (this can happen multiple times during
a blkback instance life cycle). On the other hand, request freeing has not
been moved, so it's only called when destroying the backend instance. Due to
this mismatch, blkback can allocate the request pool multiple times, without
freeing it.

In order to fix it, move the freeing of requests to xen_blkif_disconnect to
restore the symmetry between request allocation and freeing.
Reported-by: Julien Grall <julien.grall@citrix.com>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Tested-by: Julien Grall <julien.grall@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: xen-devel@lists.xenproject.org
CC: stable@vger.kernel.org # 4.2
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

This patch enables the PRCHK and reftag support when PRACT bit is set, and
block layer integrity is disabled.
Signed-off-by: Alok Pandey <pandey.alok@samsung.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

Removing unreachable code from nvme_abort_req as nvme_submit_cmd has no
failure status to return.
Signed-off-by: Sunad Bhandary <sunad.s@samsung.com>
Acked-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

Controllers can perform optional subsystem resets as introduced in NVMe
1.1. This patch adds an IOCTL to trigger the subsystem reset by writing
"NVMe" to the NSSR register.
Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
Acked-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

Controllers part of an NVMe subsystem may be reset by any other controller
in the subsystem. If the device is capable of subsystem resets, this
patch adds detection for such events and performs appropriate controller
initialization upon subsystem reset detection.

The register bit is a RW1C type, so the driver needs to write a 1 to the
status bit to clear the subsystem reset occured bit during initialization.
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

The logic in nvme_dev_add to enumerate namespaces was moved to
nvme_dev_scan. When moved, the nn variable is no longer used. This patch
removes it.

Fixes: a5768aa8i ("NVMe: Automatic namespace rescan")
Signed-off-by: Matias Bjørling <m@bjorling.me>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

This sets the queue's max segment size to match the device's
capabilities. The default of 128 is usable until a device's transfer
capability exceeds 512k, assuming a device page size of 4k. Many nvme
devices exceed that transfer limit, so this lets the block layer know what
kind of commands it to allow to form rather than unnecessarily split them.

One additional segment is added to account for a transfer that may start
in the middle of a page.
Signed-off-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

The flags variable is used as u32 variable. This patch changes the type
to be u32.
Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

This patch renames functions so that it is clear what the function does.
Otherwise it is not directly understandable what for example 'do_it' means.
Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Acked-by: Pavel Machek  <pavel@ucw.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>

Add some debugfs files that help to understand the internal state of
NBD. This exports the different sizes, flags, tasks and so on.
Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

This patch uses nbd->task_recv to determine the value of the previously
used variable 'pid' for sysfs.
Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

This message was a warning without a reason. This patch moves it into
nbd_clear_que and transforms it to a debug message.
Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

Instead of a variable 'harderror' we can simply try to correctly
propagate errors to the userspace.

This patch removes the harderror variable and passes errors through
error pointers and nbd_do_it back to the userspace.
Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>

This patch restructures sock_shutdown to avoid having the main code path
in an if block.
Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>

Move the conditional lock from sock_shutdown into the surrounding code.
Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>

At the moment the nbd timeout just detects hanging tcp operations. This
is not enough to detect a hanging or bad connection as expected of a
timeout.

This patch redesigns the timeout detection to include some more cases.
The timeout is now in relation to replies from the server. If the server
does not send replies within the timeout the connection will be shut
down.

The patch adds a continous timer 'timeout_timer' that is setup in one of
two cases:
 - The request list is empty and we are sending the first request out to
   the server. We want to have a reply within the given timeout,
   otherwise we consider the connection to be dead.
 - A server response was received. This means the server is still
   communicating with us. The timer is reset to the timeout value.

The timer is not stopped if the list becomes empty. It will just trigger
a timeout which will directly leave the handling routine again as the
request list is empty.

The whole patch does not use any additional explicit locking. The
list_empty() calls are safe to be used concurrently. The timer is locked
internally as we just use mod_timer and del_timer_sync().

The patch is based on the idea of Michal Belczyk with a previous
different implementation.

Cc: Michal Belczyk <belczyk@bsd.krakow.pl>
Cc: Hermann Lauer <Hermann.Lauer@iwr.uni-heidelberg.de>
Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Tested-by: Hermann Lauer <Hermann.Lauer@iwr.uni-heidelberg.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

Uses div_u64 for u64 division and round_down, a bitwise operation,
instead of rounddown, which uses a modulus.
Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

Some controllers have a controller-side memory buffer available for use
for submissions, completions, lists, or data.

If a CMB is available, the entire CMB will be ioremapped and it will
attempt to map the IO SQes onto the CMB. The queues will be shrunk as
needed. The CMB will not be used if the queue depth is shrunk below some
threshold where it may have reduced performance over a larger queue
in system memory.
Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

This patch changes sq_cmd writers to instead create their command on
the stack. __nvme_submit_cmd copies the sq entry to the queue and writes
the doorbell.
Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

Lots of devices support huge discard sizes these days. Depending
on how the device handles them internally, huge discards can
introduce massive latencies (hundreds of msec) on the device side.

We have a sysfs file, discard_max_bytes, that advertises the max
hardware supported discard size. Make this writeable, and split
the settings into a soft and hard limit. This can be set from
'discard_granularity' and up to the hardware limit.

Add a new sysfs file, 'discard_max_hw_bytes', that shows the hw
set limit.
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

Some drivers use it now, others just set the limits field manually.
But in preparation for splitting this into a hard and soft limit,
ensure that they all call the proper function for setting the hw
limit for discards.
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

Percpu refcount is the perfect match for partition's case,
and the conversion is quite straight.

With the convertion, one pair of atomic inc/dec can be saved
for accounting block I/O, which is run in hot path of block I/O.
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>

So the helper can be used in both generic partition
case and part0 case.
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

Pull power management and ACPI fixes from Rafael Wysocki:
 "These fix two bugs in the cpufreq core (including one recent
  regression), fix a 4.0 PCI regression related to the ACPI resources
  management and quieten an RCU-related lockdep complaint about a
  tracepoint in the suspend-to-idle code.

  Specifics:

   - Fix a recently introduced issue in the cpufreq policy object
     reinitialization that leads to CPU offline/online breakage (Viresh
     Kumar)

   - Make it possible to access frequency tables of offline CPUs which
     is needed by thermal management code among other things (Viresh
     Kumar)

   - Fix an ACPI resource management regression introduced during the
     4.0 cycle that may cause incorrect resource validation results to
     appear in 32-bit x86 kernels due to silent truncation of 64-bit
     values to 32-bit (Jiang Liu)

   - Fix up an RCU-related lockdep complaint about suspicious RCU usage
     in idle caused by using a suspend tracepoint in the core suspend-
     to-idle code (Rafael J Wysocki)"

* tag 'pm+acpi-4.2-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI / PCI: Fix regressions caused by resource_size_t overflow with 32-bit kernel
  cpufreq: Allow freq_table to be obtained for offline CPUs
  cpufreq: Initialize the governor again while restoring policy
  suspend-to-idle: Prevent RCU from complaining about tick_freeze()

Merge tag 'platform-drivers-x86-v4.2-3' of git://git.infradead.org/users/dvhart/linux-platform-drivers-x86

Pull x86 platform driver fixes from Darren Hart:
 "Fix SMBIOS call handling and hwswitch state coherency in the
  dell-laptop driver.  Cleanups for intel_*_ipc drivers.  Details:

  dell-laptop:
   - Do not cache hwswitch state
   - Check return value of each SMBIOS call
   - Clear buffer before each SMBIOS call

  intel_scu_ipc:
   - Move local memory initialization out of a mutex

  intel_pmc_ipc:
   - Update kerneldoc formatting
   - Fix compiler casting warnings"

* tag 'platform-drivers-x86-v4.2-3' of git://git.infradead.org/users/dvhart/linux-platform-drivers-x86:
  intel_scu_ipc: move local memory initialization out of a mutex
  intel_pmc_ipc: Update kerneldoc formatting
  dell-laptop: Do not cache hwswitch state
  dell-laptop: Check return value of each SMBIOS call
  dell-laptop: Clear buffer before each SMBIOS call
  intel_pmc_ipc: Fix compiler casting warnings

Pull m68knommu/coldfire fixes from Greg Ungerer:
 "Contains build fixes and updates for the ColdFire defconfigs.

  Specifically there is a couple of fixes that address problems building
  allnoconfig.  Also fix for enabling PCI bus on the M54xx family of
  ColdFire"

* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu:
  m68k: enable PCI support for m5475evb defconfig
  m68k: fix io functions for ColdFire/MMU/PCI case
  m68knommu: update defconfig for ColdFire m5475evb
  m68knommu: update defconfig for ColdFire m5407c3
  m68knommu: update defconfig for ColdFire m5307c3
  m68knommu: update defconfig for ColdFire m5275evb
  m68knommu: update defconfig for ColdFire m5272c3
  m68knommu: update defconfig for ColdFire m5249evb
  m68knommu: update defconfig for m5208evb
  m68knommu: make ColdFire SoC selection a choice
  m68knommu: improve the clock configuration defaults
  m68knommu: force setting of CONFIG_CLOCK_FREQ for ColdFire

Pull block fixes from Jens Axboe:
 "A collection of fixes from the last few weeks that should go into the
  current series.  This contains:

   - Various fixes for the per-blkcg policy data, fixing regressions
     since 4.1.  From Arianna and Tejun

   - Code cleanup for bcache closure macros from me.  Really just
     flushing this out, it's been sitting in another branch for months

   - FIELD_SIZEOF cleanup from Maninder Singh

   - bio integrity oops fix from Mike

   - Timeout regression fix for blk-mq from Ming Lei"

* 'for-linus' of git://git.kernel.dk/linux-block:
  blk-mq: set default timeout as 30 seconds
  NVMe: Reread partitions on metadata formats
  bcache: don't embed 'return' statements in closure macros
  blkcg: fix blkcg_policy_data allocation bug
  blkcg: implement all_blkcgs list
  blkcg: blkcg_css_alloc() should grab blkcg_pol_mutex while iterating blkcg_policy[]
  blkcg: allow blkcg_pol_mutex to be grabbed from cgroup [file] methods
  block/blk-cgroup.c: free per-blkcg data when freeing the blkcg
  block: use FIELD_SIZEOF to calculate size of a field
  bio integrity: do not assume bio_integrity_pool exists if bioset exists

Pull jfs fixes from David Kleikamp:
 "A couple trivial fixes and an error path fix"

* tag 'jfs-4.2' of git://github.com/kleikamp/linux-shaggy:
  jfs: clean up jfs_rename and fix out of order unlock
  jfs: fix indentation on if statement
  jfs: removed a prohibited space after opening parenthesis

* pm-cpuidle:
  suspend-to-idle: Prevent RCU from complaining about tick_freeze()

* pm-cpufreq:
  cpufreq: Allow freq_table to be obtained for offline CPUs
  cpufreq: Initialize the governor again while restoring policy

* acpi-resources:
  ACPI / PCI: Fix regressions caused by resource_size_t overflow with 32-bit kernel

It is reasonable to set default timeout of request as 30 seconds instead of
30000 ticks, which may be 300 seconds if HZ is 100, for example, some arm64
based systems may choose 100 HZ.
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Fixes: c76cbbcf ("blk-mq: put blk_queue_rq_timeout together in blk_mq_init_queue()"
Signed-off-by: Jens Axboe <axboe@fb.com>

Pull TPM bugfixes from James Morris.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  tpm, tpm_crb: fail when TPM2 ACPI table contents look corrupted
  tpm: Fix initialization of the cdev

Pull rdma fixes from Doug Ledford:
 "Mainly fix-ups for the various 4.2 items"

* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dledford/rdma: (24 commits)
  IB/core: Destroy ocrdma_dev_id IDR on module exit
  IB/core: Destroy multcast_idr on module exit
  IB/mlx4: Optimize do_slave_init
  IB/mlx4: Fix memory leak in do_slave_init
  IB/mlx4: Optimize freeing of items on error unwind
  IB/mlx4: Fix use of flow-counters for process_mad
  IB/ipath: Convert use of __constant_<foo> to <foo>
  IB/ipoib: Set MTU to max allowed by mode when mode changes
  IB/ipoib: Scatter-Gather support in connected mode
  IB/ucm: Fix bitmap wrap when devnum > IB_UCM_MAX_DEVICES
  IB/ipoib: Prevent lockdep warning in __ipoib_ib_dev_flush
  IB/ucma: Fix lockdep warning in ucma_lock_files
  rds: rds_ib_device.refcount overflow
  RDMA/nes: Fix for incorrect recording of the MAC address
  RDMA/nes: Fix for resolving the neigh
  RDMA/core: Fixes for port mapper client registration
  IB/IPoIB: Fix bad error flow in ipoib_add_port()
  IB/mlx4: Do not attemp to report HCA clock offset on VFs
  IB/cm: Do not queue work to a device that's going away
  IB/srp: Avoid using uninitialized variable
  ...

This patch has the driver automatically reread partitions if a namespace
has a separate metadata format. Previously revalidating a disk was
sufficient to get the correct capacity set on such formatted drives,
but partitions that may exist would not have been surfaced.
Reported-by: Paul Grabinar <paul.grabinar@ranbarg.com>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Tested-by: Paul Grabinar <paul.grabinar@ranbarg.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

Pull file locking updates from Jeff Layton:
 "I had thought that I was going to get away without a pull request this
  cycle.  There was a NFSv4 file locking problem that cropped up that I
  tried to fix in the NFSv4 code alone, but that fix has turned out to
  be problematic.  These patches fix this in the correct way.

  Note that this touches some NFSv4 code as well.  Ordinarily I'd wait
  for Trond to ACK this, but he's on holiday right now and the bug is
  rather nasty.  So I suggest we merge this and if he raises issues with
  it we can sort it out when he gets back"
Acked-by: Bruce Fields <bfields@fieldses.org>
Acked-by: Dan Williams <dan.j.williams@intel.com>
 [ +1 to this series fixing a 100% reproducible slab corruption +
   general protection fault in my nfs-root test environment. - Dan ]
Acked-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

* tag 'locks-v4.2-1' of git://git.samba.org/jlayton/linux:
  locks: inline posix_lock_file_wait and flock_lock_file_wait
  nfs4: have do_vfs_lock take an inode pointer
  locks: new helpers - flock_lock_inode_wait and posix_lock_inode_wait
  locks: have flock_lock_file take an inode pointer instead of a filp
  Revert "nfs: take extra reference to fl->fl_file when running a LOCKU operation"

Pull KVM fixes from Paolo Bonzini:

 - Fix FPU refactoring ("kvm: x86: fix load xsave feature warning")

 - Fix eager FPU mode (Cc stable)

 - AMD bits of MTRR virtualization

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  kvm: x86: fix load xsave feature warning
  KVM: x86: apply guest MTRR virtualization on host reserved pages
  KVM: SVM: Sync g_pat with guest-written PAT value
  KVM: SVM: use NPT page attributes
  KVM: count number of assigned devices
  KVM: VMX: fix vmwrite to invalid VMCS
  KVM: x86: reintroduce kvm_is_mmio_pfn
  x86: hyperv: add CPUID bit for crash handlers

Pull ARC fixes from Vineet Gupta:
 - Makefile changes (top-level+ARC) reinstates -O3 builds (regression
   since 3.16)
 - IDU intc related fixes, IRQ affinity
 - patch to make bitops safer for ARC
 - perf fix from Alexey to remove signed PC braino
 - Futex backend gets llock/scond support

* tag 'arc-v4.2-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc:
  ARCv2: support HS38 releases
  ARC: make sure instruction_pointer() returns unsigned value
  ARC: slightly refactor macros for boot logging
  ARC: Add llock/scond to futex backend
  arc:irqchip: prepare for drivers/irqchip/irqchip.h removal
  ARC: Make ARC bitops "safer" (add anti-optimization)
  ARCv2: [axs103] bump CPU frequency from 75 to 90 MHZ
  ARCv2: intc: IDU: Fix potential race in installing a chained IRQ handler
  ARCv2: intc: IDU: support irq affinity
  ARC: fix unused var wanring
  ARC: Don't memzero twice in dma_alloc_coherent for __GFP_ZERO
  ARC: Override toplevel default -O2 with -O3
  kbuild: Allow arch Makefiles to override {cpp,ld,c}flags
  ARCv2: guard SLC DMA ops with spinlock
  ARC: Kconfig: better way to disable ARC_HAS_LLSC for ARC_CPU_750D

Pull s390 fixes from Martin Schwidefsky:
 "One improvement for the zcrypt driver, the quality attribute for the
  hwrng device has been missing.  Without it the kernel entropy seeding
  will not happen automatically.

  And six bug fixes, the most important one is the fix for the vector
  register corruption due to machine checks"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/nmi: fix vector register corruption
  s390/process: fix sfpc inline assembly
  s390/dasd: fix kernel panic when alias is set offline
  s390/sclp: clear upper register halves in _sclp_print_early
  s390/oprofile: fix compile error
  s390/sclp: fix compile error
  s390/zcrypt: enable s390 hwrng to seed kernel entropy

The end of jfs_rename(), which is also used by the error paths,
included a call to IWRITE_UNLOCK(new_ip) after labels out1, out2
and out3. If we come in through these labels, IWRITE_LOCK() has not
been called yet.

In moving that call to the correct spot, I also moved some
exceptional truncate code earlier as well, since the early error
paths don't need to deal with it, and I renamed out4: to out_tx: so
a future patch by Jan Kara doesn't need to deal with renumbering or
confusing out-of-order labels.
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>

Pull final init.h/module.h code relocation from Paul Gortmaker:
 "With the release of 4.2-rc2 done, we should not be seeing any new code
  added that gets upset by this small code move, and we've banked yet
  another complete week of testing with this move in place on top of
  4.2-rc1 via linux-next to ensure that remained true.

  Given that, I'd like to put it in now so that people formulating new
  work for 4.3-rc1 will be exposed to the ever so slightly stricter (but
  sensible) requirements wrt.  whether they are needing init.h vs.
  module.h macros, even if they are not using linux-next.

  The diffstat of the move is slightly asymmetrical due to needing to
  leave behind a couple #ifdef in the old location and add the same ones
  to the new location, but other than that, it is a 1:1 move, complete
  with the module_init/exit trailing semicolon that we can't fix.  That
  is, until/unless someone does a tree-wide sed fix of all the
  approximately 800 currently in tree users relying on it"

* tag 'module-final-v4.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux:
  module: relocate module_init from init.h to module.h