After feedback from the hardware team, now we set the GPU min/idel freq to RPe.
Punit is expecting us to operate GPU between Rpe & Rp0. If we drop the
frequency to RPn, punit is failing to change the vgg input voltage to
minimum :(

Since Punit validates the rps range [RPe, RP0]. This patch
removes unused cherryview_rps_min_freq function.

v2: Change commit message

v3: set min_freq before idle_freq (chris)

v4: Squash 'Remove unused rps min function' patch
Signed-off-by: Deepak S <deepak.s@linux.intel.com>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

It is observed on BSW that requesting a new frequency from Punit
does nothing when the GPU is in rc6, and if we let GPU enter rc6
with a high frequency, Vnn remains slightly higher than at minimum
frequency. Extending vlv_set_rps_idle() workaround on CHV/BSW.

v2: Update commit msg (Ville)
suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Deepak S <deepak.s@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

When GPU is idle on VLV, Request freq to punit should be good enough to
get the voltage back to VNN. Also, make sure gfx clock force applies
before requesting the freq fot vlv.

v2: Do forcewake before setting idle frequency (ville)
    Update function comments to match the code (Deepak)

v3: Fix get/put across idle frequency Request. (Ville)

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=75244suggested-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Deepak S <deepak.s@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

As we're doing throughout the code, being optimistic that platform n + 1
will mostly reuse the same things as platform n allows us to minimize
the enabling work needed.

This time, it's about the number of WM levels.
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

With the recent modeset internal rework, we wind up setting crtc_state->enable
to false, but leave crtc_state->active as true following a
drmModeSetCrtc(fb=0), which is incorrect.  This mismatch gets caught by
drm_atomic_crtc_check() and causes subsequent atomic operations (such as plane
updates while the CRTC is disabled) to fail.

Bisect points to

        commit dad9a7d6d96630182fb52aae7c3856e9e7285e13
        Author: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
        Date:   Tue Apr 21 17:13:19 2015 +0300

            drm/i915: Use atomic helpers for computing changed flags

as the commit that actually triggers the regression.

The difference compared to (which this patch reverts)

commit 90d46906
Author: Matt Roper <matthew.d.roper@intel.com>
Date:   Thu May 7 14:31:28 2015 -0700

    drm/i915: Set crtc_state->active to false when CRTC is disabled (v2)

is that we know keep state->active/enable in sync for all legacy
modeset paths, as it should be.

Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Reported-and-Tested-by: Kenneth Graunke <kenneth@whitecape.org>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
[danvet: Directly squash in the revert and augment the commit
message.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Revert "drm/i915: Set crtc_state->active to false when CRTC is disabled (v2)"

This reverts commit 90d46906.

Skylake nv12 format requires dbuf (aka. ddb) calculations
and programming for each of y and uv sub-planes. Made minor
changes to reuse current dbuf calculations and programming
for uv plane. i.e., with this change, existing computation
is used for either packed format or uv portion of nv12
depending on incoming format. Added new code for dbuf
computation and programming for y plane.

This patch is a pre-requisite for adding NV12 format support.
Actual nv12 support is coming in later patches.
Signed-off-by: Chandra Konduru <chandra.konduru@intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

This patch fix spelling typo in intel_runtime_pm.c
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Lost in

commit c5ad54cf
Author: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Date:   Wed May 6 14:36:09 2015 +0300

    drm/i915: Use partial view in mmap fault handler

Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

We picked up a silent conflict in amdkfd with drm-fixes and drm-next,
backmerge v4.1-rc5 and fix the conflicts
Signed-off-by: Dave Airlie <airlied@redhat.com>

Conflicts:
	drivers/gpu/drm/drm_irq.c

- Add the interrupts & events modules, including new IOCTLs to create and wait
  on events. The HSA RT open source stack is mainly using events to know when
  a dispatched work has been completed. In addition, this module is
  a pre-requisite for the next module I'm going to upstream - debugger support

  This module also handles H/W exceptions, such as memory exception received
  through the IOMMUv2 H/W and Bad Opcode exception receieved from the GPU.

- Adding a new kernel module parameter to let the user decide whether he wants
  to receive a SIGTERM when a memory exception occurs inside the GPU kernel and
  the HSA application doesn't wait on an appropriate event, or if he just want
  to receive notification about this event in dmesg. The default is the latter.

- Additional improvements for SDMA code

- Update my email address in Maintainers file.

* tag 'drm-amdkfd-next-2015-05-19' of git://people.freedesktop.org/~gabbayo/linux:
  drm/amdkfd: change driver version to 0.7.2
  drm/amdkfd: Implement events IOCTLs
  drm/amdkfd: Add module parameter of send_sigterm
  drm/amdkfd: Add bad opcode exception handling
  drm/amdkfd: Add memory exception handling
  drm/amdkfd: Add the events module
  drm/amdkfd: add events IOCTL set definitions
  drm/amdkfd: Add interrupt handling module
  drm/radeon: Add init interrupt kfd->kgd interface
  MAINTAINERS: update amdkfd Oded's email address
  drm/amdkfd: make the sdma vm init to be asic specific
  drm/amdkfd: Use new struct for asic specific ops
  drm/amdkfd: reformat some debug prints
  drm/amdkfd: Remove unessary void pointer cast

Scattering of random drm core patches. Bunch of atomic prep work too, but
the final bits for blob properties, atomic modesets and lifting the
experimental tag on the atomic ioctl are still blocked on Daniel Stone
finalizing and testing the weston support for it. I hope that we can get
it all ready for 4.2 though.

* tag 'topic/drm-misc-2015-05-19' of git://anongit.freedesktop.org/drm-intel: (22 commits)
  drm/atomic: Allow drivers to subclass drm_atomic_state, v3
  drm/atomic: remove duplicated assignment of old_plane_state
  drm/dp: Fix comment in DP helper
  drm/atomic: add drm_atomic_get_existing_*_state helpers
  drm/core: get rid of -Iinclude/drm
  drm/i915: get rid of -Iinclude/drm
  drm/atomic-helpers: Export drm_atomic_helper_update_legacy_modeset_state
  drm/atomic-helpers: Update vblank timestamping constants
  drm/sysfs: remove unnecessary connector type checks
  drm/sysfs: split DVI-I and TV-out attributes
  drm/sysfs: make optional attribute groups per connector type
  drm/sysfs: add a helper for extracting connector type from kobject
  drm/edid: Add CEA modes before inferred modes
  drm/prime: Allow internal imports without import_sg_table
  drm: Add reference counting to blob properties
  drm: Introduce blob_lock
  drm: Introduce helper for replacing blob properties
  drm: Don't leak path blob property when updating
  drm/atomic: Don't open-code CRTC state destroy
  drm/edid: Add DMT modes with ID > 0x50
  ...

Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>

Signed-off-by: Andrew Lewycky <Andrew.Lewycky@amd.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>

This patch adds a new kernel module parameter to amdkfd,
called send_sigterm.

This parameter specifies whether amdkfd should send the
SIGTERM signal to an HSA process, when the following conditions
occur:

1. The GPU triggers an exception regarding a kernel that was
   issued by this process.

2. The HSA process isn't waiting on an event that handles
   this exception.

The default behavior is not to send a SIGTERM and suffice
with a dmesg error print.
Reviewed-by: Ben Goz <ben.goz@amd.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>

Signed-off-by: Alexey Skidanov <alexey.skidanov@gmail.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>

This patch adds Peripheral Page Request (PPR) failure processing
and reporting.

Bad address or pointer to a system memory block with inappropriate
read/write permission cause such PPR failure during a user queue
processing. PPR request handling is done by IOMMU driver notifying
AMDKFD module on PPR failure.

The process triggering a PPR failure will be notified by
appropriate event or SIGTERM signal will be sent to it.

v3:
- Change all bool fields in struct kfd_memory_exception_failure to
  uint32_t
Signed-off-by: Alexey Skidanov <alexey.skidanov@gmail.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>

This patch adds the events module (kfd_events.c) and the interrupt
handle module for Kaveri (cik_event_interrupt.c).

The patch updates the interrupt_is_wanted(), so that it now calls the
interrupt isr function specific for the device that received the
interrupt. That function(implemented in cik_event_interrupt.c)
returns whether this interrupt is of interest to us or not.

The patch also updates the interrupt_wq(), so that it now calls the
device's specific wq function, which checks the interrupt source
and tries to signal relevant events.

v2:

Increase limit of signal events to 4096 per process
Remove bitfields from struct cik_ih_ring_entry
Rename radeon_kfd_event_mmap to kfd_event_mmap
Add debug prints to allocate_free_slot and allocate_signal_page
Make allocate_event_notification_slot return a correct value
Add warning prints to create_signal_event
Remove error print from IOCTL path
Reformatted debug prints in kfd_event_mmap
Map correct size (as received from mmap) in kfd_event_mmap

v3:

Reduce limit of signal events back to 256 per process
Fix allocation of kernel memory for signal events
Signed-off-by: Andrew Lewycky <Andrew.Lewycky@amd.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>

- AMDKFD_IOC_CREATE_EVENT:
	Creates a new event of a specified type

- AMDKFD_IOC_DESTROY_EVENT:
	Destroys an existing event

- AMDKFD_IOC_SET_EVENT:
	Signal an existing event

- AMDKFD_IOC_RESET_EVENT:
	Reset an existing event

- AMDKFD_IOC_WAIT_EVENTS:
	Wait on event(s) until they are signaled

v2:

- Move the limit of the signal events to kfd_ioctl.h so it
  can be used by userspace

v3:
- Change all bool fields in struct kfd_memory_exception_failure
to uint32_t
Signed-off-by: Andrew Lewycky <Andrew.Lewycky@amd.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>

This patch adds the interrupt handling module, kfd_interrupt.c, and its
related members in different data structures to the amdkfd driver.

The amdkfd interrupt module maintains an internal interrupt ring
per amdkfd device. The internal interrupt ring contains interrupts
that needs further handling. The extra handling is deferred to
a later time through a workqueue.

There's no acknowledgment for the interrupts we use. The hardware
simply queues a new interrupt each time without waiting.

The fixed-size internal queue means that it's possible for us to lose
interrupts because we have no back-pressure to the hardware.

However, only interrupts that are "wanted" by amdkfd, are copied into
the amdkfd s/w interrupt ring, in order to minimize the chances
for overflow of the ring.
Signed-off-by: Andrew Lewycky <Andrew.Lewycky@amd.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>

This patch adds a new interface function to the kfd->kgd interface.
The function is kgd_init_interrupts() and its function is to
initialize a pipe's interrupts.

The function currently enables the timestamp interrupt and the
bad opcode interrupt.
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>

Leaving AMD soon so need to update my email address to @gmail.com
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>

Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>

This patch creates a new structure for asic specific operations, instead
of using the existing structure of operations.

This is done to make the code flow more logic, readable and maintainable.

The change is done only to the device queue manager module at this point.
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>

Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>

kmalloc() returns a void pointer - no need to cast it in
drivers/gpu/drm/amd/amdkfd/kfd_process.c::kfd_process_destroy_delayed()
Signed-off-by: Firo Yang <firogm@gmail.com>
Signed-off-by: Oded Gabbay <oded.gabbay@amd.com>

- skl plane scaler support (Chandra Kondru)
- enable hsw cmd parser (Daniel and fix from Rebecca Palmer)
- skl dc5/6 support (low power display modes) from Suketu&Sunil
- dp compliance testing patches (Todd Previte)
- dp link training optimization (Mika Kahola)
- fixes to make skl resume work (Damien)
- rework modeset code to fully use atomic state objects (Ander&Maarten)
- pile of bxt w/a patchs from Nick Hoath
- (linear) partial gtt mmap support (Joonas Lahtinen)

* tag 'drm-intel-next-2015-05-08' of git://anongit.freedesktop.org/drm-intel: (103 commits)
  drm/i915: Update DRIVER_DATE to 20150508
  drm/i915: Only wait for required lanes in vlv_wait_port_ready()
  drm/i915: Fix possible security hole in command parsing
  drm/edid: Kerneldoc for newly added edid_corrupt
  drm/i915: Reject huge tiled objects
  Revert "drm/i915: Hack to tie both common lanes together on chv"
  drm/i915: Work around DISPLAY_PHY_CONTROL register corruption on CHV
  drm/i915: Implement chv display PHY lane stagger setup
  drm/i915/vlv: remove wait for previous GFX clk disable request
  drm/i915: Set crtc_state->active to false when CRTC is disabled (v2)
  drm/i915/skl: Re-indent part of skl_ddi_calculate_wrpll()
  drm/i915: Use partial view in mmap fault handler
  drm/i915: Add a partial GGTT view type
  drm/i915: Consider object pinned if any VMA is pinned
  drm/i915: Do not make assumptions on GGTT VMA sizes
  drm/i915/bxt: Mark WaCcsTlbPrefetchDisable as for Broxton also.
  drm/i915/bxt: Mark WaDisablePartialResolveInVc as for Broxton also.
  drm/i915/bxt: Mark Wa4x4STCOptimizationDisable as for Broxton also.
  drm/i915/bxt: Move WaForceEnableNonCoherent to Skylake only
  drm/i915/bxt: Enable WaEnableYV12BugFixInHalfSliceChicken7 for Broxton
  ...

Two watchdog changes that came through different trees had a non
conflicting conflict, that is, one changed the semantics of a variable
but no actual code conflict happened. So the merge appeared fine, but
the resulting code did not behave as expected.

Commit 195daf66 ("watchdog: enable the new user interface of the
watchdog mechanism") changes the semantics of watchdog_user_enabled,
which thereafter is only used by the functions introduced by
b3738d29 ("watchdog: Add watchdog enable/disable all functions").

There further appears to be a distinct lack of serialization between
setting and using watchdog_enabled, so perhaps we should wrap the
{en,dis}able_all() things in watchdog_proc_mutex.

This patch fixes a s2r failure reported by Michal; which I cannot
readily explain. But this does make the code internally consistent
again.
Reported-and-tested-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull MTD fixes from Brian Norris:
 "Two MTD fixes for 4.1:

   - readtest: the signal-handling code was clobbering the error codes
     we should be handling/reporting in this test, rendering it useless.
     Noticed by Coverity.

   - the common SPI NOR flash DT binding (merged for 4.1-rc1) is being
     revised, so let's change that before 4.1 is minted"

* tag 'for-linus-20150516' of git://git.infradead.org/linux-mtd:
  Documentation: dt: mtd: replace "nor-jedec" binding with "jedec, spi-nor"
  mtd: readtest: don't clobber error reports

Drivers may need to store the state of shared resources, such as PLLs
or FIFO space, into the atomic state. Allow this by making it possible
to subclass drm_atomic_state.

Changes since v1:
- Change member names for functions to atomic_state_(alloc,clear)
- Change __drm_atomic_state_new to drm_atomic_state_init
- Allow free function to be overridden too, in case extra memory is
  allocated in alloc.
Changes since v2:
- Rename *_default_free to default_release, to make clear it doesn't
  free the state object itself.

Cc: dri-devel@lists.freedesktop.org
Acked-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

old_plane_state is already assigned to old_state->plane_states[i] inside
for_each_plane_in_state(). Here we remove an the extra assignment.
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Commit 4f71d0cb ("drm/dp: add a hw mutex around the transfer
functions. (v2)"), renamed the functions drm_dp_aux_register_i2c_bus()
and drm_dp_aux_unregister_i2c_bus() to drm_dp_aux_register() and
drm_dp_aux_unregister(), respectively. However, a comment referring to
the original names was not updated in the DP helper header file. Hence,
correct these names.
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Pull USB fixes from Greg KH:
 "Here are some USB fixes and new device ids for 4.1-rc4.

  All are pretty minor, and have been in linux-next successfully"

* tag 'usb-4.1-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
  usb-storage: Add NO_WP_DETECT quirk for Lacie 059f:0651 devices
  Added another USB product ID for ELAN touchscreen quirks.
  xhci: gracefully handle xhci_irq dead device
  xhci: Solve full event ring by increasing TRBS_PER_SEGMENT to 256
  xhci: fix isoc endpoint dequeue from advancing too far on transaction error
  usb: chipidea: debug: avoid out of bound read
  USB: visor: Match I330 phone more precisely
  USB: pl2303: Remove support for Samsung I330
  USB: cp210x: add ID for KCF Technologies PRN device
  usb: gadget: remove incorrect __init/__exit annotations
  usb: phy: isp1301: work around tps65010 dependency
  usb: gadget: serial: fix re-ordering of tx data
  usb: gadget: hid: Fix static variable usage
  usb: gadget: configfs: Fix interfaces array NULL-termination
  usb: gadget: xilinx: fix devm_ioremap_resource() check
  usb: dwc3: dwc3-omap: correct the register macros

Pull tty/serial fixes from Greg KH:
 "Here's some TTY and serial driver fixes for reported issues.

  All of these have been in linux-next successfully"

* tag 'tty-4.1-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  pty: Fix input race when closing
  tty/n_gsm.c: fix a memory leak when gsmtty is removed
  Revert "serial/amba-pl011: Leave the TX IRQ alone when the UART is not open"
  serial: omap: Fix error handling in probe
  earlycon: Revert log warnings

Pull staging / IIO driver fixes from Greg KH:
 "Here's some staging and iio driver fixes to resolve a number of
  reported issues.

  All of these have been in linux-next for a while"

* tag 'staging-4.1-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging: (31 commits)
  iio: light: hid-sensor-prox: Fix memory leak in probe()
  iio: adc: cc10001: Add delay before setting START bit
  iio: adc: cc10001: Fix regulator_get_voltage() return value check
  iio: adc: cc10001: Fix incorrect use of power-up/power-down register
  staging: gdm724x: Correction of variable usage after applying ALIGN()
  iio: adc: cc10001: Fix the channel number mapping
  staging: vt6655: lock MACvWriteBSSIDAddress.
  staging: vt6655: CARDbUpdateTSF bss timestamp correct tsf counter value.
  staging: vt6655: vnt_tx_packet Correct TX order of OWNED_BY_NIC
  staging: vt6655: Fix 80211 control and management status reporting.
  staging: vt6655: implement IEEE80211_TX_STAT_NOACK_TRANSMITTED
  staging: vt6655: device_free_tx_buf use only ieee80211_tx_status_irqsafe
  staging: vt6656: use ieee80211_tx_info to select packet type.
  staging: rtl8712: freeing an ERR_PTR
  staging: sm750: remove incorrect __exit annotation
  iio: kfifo: Set update_needed to false only if a buffer was allocated
  iio: mcp320x: Fix occasional incorrect readings
  iio: accel: mma9553: check input value for activity period
  iio: accel: mma9553: add enable channel for activity
  iio: accel: mma9551_core: prevent buffer overrun
  ...

Pull char/misc fix from Greg KH:
 "Here is one fix, in the extcon subsystem, that resolves a reported
  issue.

  It's been in linux-next for a number of weeks now, sorry for not
  getting it to you sooner"

* tag 'char-misc-4.1-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
  extcon: usb-gpio: register extcon device before IRQ registration

Pull UML hostfs fix from Richard Weinberger:
 "This contains a single fix for a regression introduced in 4.1-rc1"

* 'for-linus-4.1-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml:
  hostfs: Use correct mask for file mode

Pull UBI bufix from Richard Weinberger:
 "This contains a single bug fix for the UBI block driver"

* tag 'upstream-4.1-rc4' of git://git.infradead.org/linux-ubifs:
  UBI: block: Add missing cache flushes

Pull ext4 fixes from Ted Ts'o:
 "Fix a number of ext4 bugs; the most serious of which is a bug in the
  lazytime mount optimization code where we could end up updating the
  timestamps to the wrong inode"

* tag 'for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: fix an ext3 collapse range regression in xfstests
  jbd2: fix r_count overflows leading to buffer overflow in journal recovery
  ext4: check for zero length extent explicitly
  ext4: fix NULL pointer dereference when journal restart fails
  ext4: remove unused function prototype from ext4.h
  ext4: don't save the error information if the block device is read-only
  ext4: fix lazytime optimization

Pull btrfs fixes from Chris Mason:
 "The first commit is a fix from Filipe for a very old extent buffer
  reuse race that triggered a BUG_ON.  It hasn't come up often, I looked
  through old logs at FB and we hit it a handful of times over the last
  year.

  The rest are other corners he hit during testing"

* 'for-linus-4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  Btrfs: fix race when reusing stale extent buffers that leads to BUG_ON
  Btrfs: fix race between block group creation and their cache writeout
  Btrfs: fix panic when starting bg cache writeout after IO error
  Btrfs: fix crash after inode cache writeback failure