We had many entries that were recently added just to allow selecting
some flashes directly but were never used. They weren't providing any
special flash handling, we just needed them due to the lack of some
generic binding string.

With the introduction of "nor-jedec" (in 1103b851) they won't be needed
unless we discover some faulty flash requiring workarounds.
As explained in m25p80 DT documentation we require specifying
"nor-jedec" now as less specific compatible entry.
Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

Use dev_pm_ops instead of the legacy suspend/resume callbacks for the MTD
class suspend and resume operations.

While we are at it slightly reorder things to avoid the need for forward
declarations.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

The platform_device_id is not modified by the driver and core uses it as
const.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski.k@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

The platform_device_id is not modified by the driver and core uses it as
const.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski.k@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

The platform_device_id is not modified by the driver and core uses it as
const.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski.k@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

In preparation to enable ARCH_MMP on ARM64, a couple of fixes are needed
to build the pxa3xx_nand driver:

Legacy DMA will only used on ARM, so also make it condtional on
CONFIG_ARM.
__raw_{read,write}sl are not available on ARM64 or generically, so use
the readsl/writesl variants instead. Somewhat inconsistently,
{read,write}sl are inherently non-swapping with the generic version
using __raw_{read,write}l.
Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: linux-mtd@lists.infradead.org
[Brian: added one more __raw_readsl -> readsl]
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

Now that the driver handles the FIFO draining in a threaded interrupt, we can
base our timeout on jiffies and sleeping, instead of using mdelay.
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

return type of wait_for_completion_timeout is unsigned long not int. An
appropriately named unsigned long is added and the assignment fixed up.
This not only should help readability but also handles corner cases
properly.
Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

wait_for_completion_timeout does not return negative values so
result handling here does not need to check for negative return.
Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

As all four bytes are written in any case the memset() is in vain.
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

of_device_id is always used as const.
(See driver.of_match_table and open firmware functions)
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

This statement was written with a cast-to-loff_t to be sure to have a
full 64-bit mask. However, we don't account for the fact that
'1 << this->bbt_erase_shift' might already overflow.

This will not be a problem in practice, since eraseblocks should never
be anywhere near 4GiB. But we can do this for completeness, and quiet
Coverity in the meantime. CID #1226806.
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

Don't leak this->bbt, and return early if check_create() fails. It helps
to have a single error path to avoid these problems.
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

This implementation detail is no longer needed outside of nand_bbt.c.
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

The diskonchip driver almost uses the default nand_base hooks as-is,
except that it provides custom on-flash BBT descriptors and avoids using
factory-marked bad blockers.

So let's refactor the BBT initialization code into a private 'late_init'
hook which handles all the private details. Note the usage of
NAND_SKIP_BBTSCAN, which allows us to defer the BBT scan until we've
prepared everything.
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

Signed-off-by: Brian Norris <computersforpeace@gmail.com>

AMD CPUs don't reinitialize the SS descriptor on SYSRET, so SYSRET with
SS == 0 results in an invalid usermode state in which SS is apparently
equal to __USER_DS but causes #SS if used.

Work around the issue by setting SS to __KERNEL_DS __switch_to, thus
ensuring that SYSRET never happens with SS set to NULL.

This was exposed by a recent vDSO cleanup.

Fixes: e7d6eefa x86/vdso32/syscall.S: Do not load __USER32_DS to %ss
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Peter Anvin <hpa@zytor.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull intel drm fixes from Dave Airlie.

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux:
  drm/i915: vlv: fix save/restore of GFX_MAX_REQ_COUNT reg
  drm/i915: Workaround to avoid lite restore with HEAD==TAIL
  drm/i915: cope with large i2c transfers

Pull intel iommu updates from David Woodhouse:
 "This lays a little of the groundwork for upcoming Shared Virtual
  Memory support — fixing some bogus #defines for capability bits and
  adding the new ones, and starting to use the new wider page tables
  where we can, in anticipation of actually filling in the new fields
  therein.

  It also allows graphics devices to be assigned to VM guests again.
  This got broken in 3.17 by disallowing assignment of RMRR-afflicted
  devices.  Like USB, we do understand why there's an RMRR for graphics
  devices — and unlike USB, it's actually sane.  So we can make an
  exception for graphics devices, just as we do USB controllers.

  Finally, tone down the warning about the X2APIC_OPT_OUT bit, due to
  persistent requests.  X2APIC_OPT_OUT was added to the spec as a nasty
  hack to allow broken BIOSes to forbid us from using X2APIC when they
  do stupid and invasive things and would break if we did.

  Someone noticed that since Windows doesn't have full IOMMU support for
  DMA protection, setting the X2APIC_OPT_OUT bit made Windows avoid
  initialising the IOMMU on the graphics unit altogether.

  This means that it would be available for use in "driver mode", where
  the IOMMU registers are made available through a BAR of the graphics
  device and the graphics driver can do SVM all for itself.

  So they started setting the X2APIC_OPT_OUT bit on *all* platforms with
  SVM capabilities.  And even the platforms which *might*, if the
  planets had been aligned correctly, possibly have had SVM capability
  but which in practice actually don't"

* git://git.infradead.org/intel-iommu:
  iommu/vt-d: support extended root and context entries
  iommu/vt-d: Add new extended capabilities from v2.3 VT-d specification
  iommu/vt-d: Allow RMRR on graphics devices too
  iommu/vt-d: Print x2apic opt out info instead of printing a warning
  iommu/vt-d: kill bogus ecap_niotlb_iunits()

Pull i2c fixes from Wolfram Sang:
 "This has a mixture of merge window cleanups and bugfixes"

* 'i2c/for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: st: add include for pinctrl
  i2c: mux: use proper dev when removing "channel-X" symlinks
  i2c: digicolor: remove duplicate include
  i2c: Mark adapter devices with pm_runtime_no_callbacks
  i2c: pca-platform: fix broken email address
  i2c: mxs: fix broken email address
  i2c: rk3x: report number of messages transmitted

Pull btrfs fixes from Chris Mason:
 "Filipe hit two problems in my block group cache patches.  We finalized
  the fixes last week and ran through more tests"

* 'for-linus-4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  Btrfs: prevent list corruption during free space cache processing
  Btrfs: fix inode cache writeout

Merge tag 'drm-intel-next-fixes-2015-04-25' of git://anongit.freedesktop.org/drm-intel into drm-fixes

three fixes for i915.

* tag 'drm-intel-next-fixes-2015-04-25' of git://anongit.freedesktop.org/drm-intel:
  drm/i915: vlv: fix save/restore of GFX_MAX_REQ_COUNT reg
  drm/i915: Workaround to avoid lite restore with HEAD==TAIL
  drm/i915: cope with large i2c transfers

Pull NFS client updates from Trond Myklebust:
 "Another set of mainly bugfixes and a couple of cleanups.  No new
  functionality in this round.

  Highlights include:

  Stable patches:
   - Fix a regression in /proc/self/mountstats
   - Fix the pNFS flexfiles O_DIRECT support
   - Fix high load average due to callback thread sleeping

  Bugfixes:
   - Various patches to fix the pNFS layoutcommit support
   - Do not cache pNFS deviceids unless server notifications are enabled
   - Fix a SUNRPC transport reconnection regression
   - make debugfs file creation failure non-fatal in SUNRPC
   - Another fix for circular directory warnings on NFSv4 "junctioned"
     mountpoints
   - Fix locking around NFSv4.2 fallocate() support
   - Truncating NFSv4 file opens should also sync O_DIRECT writes
   - Prevent infinite loop in rpcrdma_ep_create()

  Features:
   - Various improvements to the RDMA transport code's handling of
     memory registration
   - Various code cleanups"

* tag 'nfs-for-4.1-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs: (55 commits)
  fs/nfs: fix new compiler warning about boolean in switch
  nfs: Remove unneeded casts in nfs
  NFS: Don't attempt to decode missing directory entries
  Revert "nfs: replace nfs_add_stats with nfs_inc_stats when add one"
  NFS: Rename idmap.c to nfs4idmap.c
  NFS: Move nfs_idmap.h into fs/nfs/
  NFS: Remove CONFIG_NFS_V4 checks from nfs_idmap.h
  NFS: Add a stub for GETDEVICELIST
  nfs: remove WARN_ON_ONCE from nfs_direct_good_bytes
  nfs: fix DIO good bytes calculation
  nfs: Fetch MOUNTED_ON_FILEID when updating an inode
  sunrpc: make debugfs file creation failure non-fatal
  nfs: fix high load average due to callback thread sleeping
  NFS: Reduce time spent holding the i_mutex during fallocate()
  NFS: Don't zap caches on fallocate()
  xprtrdma: Make rpcrdma_{un}map_one() into inline functions
  xprtrdma: Handle non-SEND completions via a callout
  xprtrdma: Add "open" memreg op
  xprtrdma: Add "destroy MRs" memreg op
  xprtrdma: Add "reset MRs" memreg op
  ...

Pull fourth vfs update from Al Viro:
 "d_inode() annotations from David Howells (sat in for-next since before
  the beginning of merge window) + four assorted fixes"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  RCU pathwalk breakage when running into a symlink overmounting something
  fix I_DIO_WAKEUP definition
  direct-io: only inc/dec inode->i_dio_count for file systems
  fs/9p: fix readdir()
  VFS: assorted d_backing_inode() annotations
  VFS: fs/inode.c helpers: d_inode() annotations
  VFS: fs/cachefiles: d_backing_inode() annotations
  VFS: fs library helpers: d_inode() annotations
  VFS: assorted weird filesystems: d_inode() annotations
  VFS: normal filesystems (and lustre): d_inode() annotations
  VFS: security/: d_inode() annotations
  VFS: security/: d_backing_inode() annotations
  VFS: net/: d_inode() annotations
  VFS: net/unix: d_backing_inode() annotations
  VFS: kernel/: d_inode() annotations
  VFS: audit: d_backing_inode() annotations
  VFS: Fix up some ->d_inode accesses in the chelsio driver
  VFS: Cachefiles should perform fs modifications on the top layer only
  VFS: AF_UNIX sockets should call mknod on the top layer only

Pull more power management and ACPI updates from Rafael Wysocki:
 "These are fixes mostly (intel_pstate, ACPI core, ACPI EC driver,
  cpupower tool), a new CPU ID for the Intel RAPL driver and one
  intel_pstate driver improvement that didn't make it to my previous
  pull requests due to timing.

  Specifics:

   - Fix a build warning in the intel_pstate driver showing up in
     non-SMP builds (Borislav Petkov)

   - Change one of the intel_pstate's P-state selection parameters for
     Baytrail and Cherrytrail CPUs to significantly improve performance
     at the cost of a small increase in energy consumption (Kristen
     Carlson Accardi)

   - Fix a NULL pointer dereference in the ACPI EC driver due to an
     unsafe list walk in the query handler removal routine (Chris
     Bainbridge)

   - Get rid of a false-positive lockdep warning in the ACPI container
     hot-remove code (Rafael J Wysocki)

   - Prevent the ACPI device enumeration code from creating device
     objects of a wrong type in some cases (Rafael J Wysocki)

   - Add Skylake processors support to the Intel RAPL power capping
     driver (Brian Bian)

   - Drop the stale MAINTAINERS entry for the ACPI dock driver that is
     regarded as part of the ACPI core and maintained along with it now
     (Chao Yu)

   - Fix cpupower tool breakage caused by a library API change in libpci
     3.3.0 (Lucas Stach)"

* tag 'pm+acpi-4.1-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI / scan: Add a scan handler for PRP0001
  ACPI / scan: Annotate physical_node_lock in acpi_scan_is_offline()
  ACPI / EC: fix NULL pointer dereference in acpi_ec_remove_query_handler()
  MAINTAINERS: remove maintainship entry of docking station driver
  powercap / RAPL: Add support for Intel Skylake processors
  cpufreq: intel_pstate: Fix an annoying !CONFIG_SMP warning
  intel_pstate: Change the setpoint for Atom params
  cpupower: fix breakage from libpci API change

Pull crypto fixes from Herbert Xu:
 "This push fixes a build problem with img-hash under non-standard
  configurations and a serious regression with sha512_ssse3 which can
  lead to boot failures"

* git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
  crypto: img-hash - CRYPTO_DEV_IMGTEC_HASH should depend on HAS_DMA
  crypto: x86/sha512_ssse3 - fixup for asm function prototype change

Merge tag 'platform-drivers-x86-v4.1-1' of git://git.infradead.org/users/dvhart/linux-platform-drivers-x86

Pull x86 platform driver updates from Darren Hart:
 "This series includes significant updates to the toshiba_acpi driver
  and the reintroduction of the dell-laptop keyboard backlight additions
  I had to revert previously.  Also included are various fixes for
  typos, warnings, correctness, and minor bugs.

  Specifics:

  dell-laptop:
     - add support for keyboard backlight.

  toshiba_acpi:
     - adaptive keyboard, hotkey, USB sleep and charge, and backlight
       updates.  Update sysfs documentation.

  toshiba_bluetooth:
     - fix enabling/disabling loop on recent devices

  apple-gmux:
     - lock iGP IO to protect from vgaarb changes

  other:
     - Fix typos, clear gcc warnings, clarify pr_* messages, correct
       return types, update MAINTAINERS"

* tag 'platform-drivers-x86-v4.1-1' of git://git.infradead.org/users/dvhart/linux-platform-drivers-x86: (25 commits)
  toshiba_acpi: Do not register vendor backlight when acpi_video bl is available
  MAINTAINERS: Add me on list of Dell laptop drivers
  platform: x86: dell-laptop: Add support for keyboard backlight
  Documentation/ABI: Update sysfs-driver-toshiba_acpi entry
  toshiba_acpi: Fix pr_* messages from USB Sleep Functions
  toshiba_acpi: Update and fix USB Sleep and Charge modes
  wmi: Use bool function return values of true/false not 1/0
  toshiba_bluetooth: Fix enabling/disabling loop on recent devices
  toshiba_bluetooth: Clean up *_add function and disable BT device at removal
  toshiba_bluetooth: Add three new functions to the driver
  toshiba_acpi: Fix the enabling of the Special Functions
  toshiba_acpi: Use the Hotkey Event Type function for keymap choosing
  toshiba_acpi: Add Hotkey Event Type function and definitions
  x86/wmi: delete unused wmi_data_lock mutex causing gcc warning
  apple-gmux: lock iGP IO to protect from vgaarb changes
  MAINTAINERS: Add missing Toshiba devices and add myself as maintainer
  toshiba_acpi: Update events in toshiba_acpi_notify
  intel-oaktrail: Fix trivial typo in comment
  thinkpad_acpi: off by one in adaptive_keyboard_hotkey_notify_hotkey()
  thinkpad_acpi: signedness bugs getting current_mode
  ...

Pull chrome platform updates from Olof Johansson:
 "Here's a set of updates to the Chrome OS platform drivers for this
  merge window.

  Main new things this cycle is:

   - Driver changes to expose the lightbar to users.  With this, you can
     make your own blinkenlights on Chromebook Pixels.

   - Changes in the way that the atmel_mxt trackpads are probed.  The
     laptop driver is trying to be smart and not instantiate the devices
     that don't answer to probe.  For the trackpad that can come up in
     two modes (bootloader or regular), this gets complicated since the
     driver already knows how to handle the two modes including the
     actual addresses used.  So now the laptop driver needs to know more
     too, instantiating the regular address even if the bootloader one
     is the probe that passed.

   - mfd driver improvements by Javier Martines Canillas, and a few
     bugfixes from him, kbuild and myself"

* tag 'chrome-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/olof/chrome-platform:
  platform/chrome: chromeos_laptop - instantiate Atmel at primary address
  platform/chrome: cros_ec_lpc - Depend on X86 || COMPILE_TEST
  platform/chrome: cros_ec_lpc - Include linux/io.h header file
  platform/chrome: fix platform_no_drv_owner.cocci warnings
  platform/chrome: cros_ec_lightbar - fix duplicate const warning
  platform/chrome: cros_ec_dev - fix Unknown escape '%' warning
  platform/chrome: Expose Chrome OS Lightbar to users
  platform/chrome: Create sysfs attributes for the ChromeOS EC
  mfd: cros_ec: Instantiate ChromeOS EC character device
  platform/chrome: Add Chrome OS EC userspace device interface
  platform/chrome: Add cros_ec_lpc driver for x86 devices
  mfd: cros_ec: Add char dev and virtual dev pointers
  mfd: cros_ec: Use fixed size arrays to transfer data with the EC

Pull arch/cris updates from Jesper Nilsson:
 "Some much needed love for the CRIS-port.

  There's a bunch of changes this time, giving the CRISv32 port a bit of
  modern makeover with device-tree, irq domain and gpiolib support, and
  more switchover to generic frameworks.

  Some small fixes and removal of the theoretical SMP support brings up
  the rear"

* tag 'cris-for-4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/jesper/cris:
  cris: fix integer overflow in ELF_ET_DYN_BASE
  CRISv32: use GENERIC_SCHED_CLOCK
  CRISv32: use MMIO clocksource
  CRISv32: use generic clockevents
  CRIS: use generic headers via Kbuild
  CRIS: use generic cmpxchg.h
  CRIS: use generic atomic.h
  CRIS: use generic atomic bitops
  CRISv10: remove redundant macros from system.h
  CRIS: remove SMP code
  CRISv32: don't enable irqs in INIT_THREAD
  CRISv32: handle multiple signals
  CRISv32: prevent bogus restarts on sigreturn
  CRISv32: don't attempt syscall restart on irq exit
  Add binding documentation for CRIS
  CRIS: add Axis 88 board device tree
  CRISv32: add device tree support
  CRISv32: add irq domains support
  CRIS: enable GPIOLIB

Pull powerpc fixes from Michael Ellerman:

 - fix for mm_dec_nr_pmds() from Scott.

 - fixes for oopses seen with KVM + THP from Aneesh.

 - build fixes from Aneesh & Shreyas.

* tag 'powerpc-4.1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/mpe/linux:
  powerpc/mm: Fix build error with CONFIG_PPC_TRANSACTIONAL_MEM disabled
  powerpc/kvm: Fix ppc64_defconfig + PPC_POWERNV=n build error
  powerpc/mm/thp: Return pte address if we find trans_splitting.
  powerpc/mm/thp: Make page table walk safe against thp split/collapse
  KVM: PPC: Remove page table walk helpers
  KVM: PPC: Use READ_ONCE when dereferencing pte_t pointer
  powerpc/hugetlb: Call mm_dec_nr_pmds() in hugetlb_free_pmd_range()

Pull second batch of KVM changes from Paolo Bonzini:
 "This mostly includes the PPC changes for 4.1, which this time cover
  Book3S HV only (debugging aids, minor performance improvements and
  some cleanups).  But there are also bug fixes and small cleanups for
  ARM, x86 and s390.

  The task_migration_notifier revert and real fix is still pending
  review, but I'll send it as soon as possible after -rc1"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (29 commits)
  KVM: arm/arm64: check IRQ number on userland injection
  KVM: arm: irqfd: fix value returned by kvm_irq_map_gsi
  KVM: VMX: Preserve host CR4.MCE value while in guest mode.
  KVM: PPC: Book3S HV: Use msgsnd for signalling threads on POWER8
  KVM: PPC: Book3S HV: Translate kvmhv_commence_exit to C
  KVM: PPC: Book3S HV: Streamline guest entry and exit
  KVM: PPC: Book3S HV: Use bitmap of active threads rather than count
  KVM: PPC: Book3S HV: Use decrementer to wake napping threads
  KVM: PPC: Book3S HV: Don't wake thread with no vcpu on guest IPI
  KVM: PPC: Book3S HV: Get rid of vcore nap_count and n_woken
  KVM: PPC: Book3S HV: Move vcore preemption point up into kvmppc_run_vcpu
  KVM: PPC: Book3S HV: Minor cleanups
  KVM: PPC: Book3S HV: Simplify handling of VCPUs that need a VPA update
  KVM: PPC: Book3S HV: Accumulate timing information for real-mode code
  KVM: PPC: Book3S HV: Create debugfs file for each guest's HPT
  KVM: PPC: Book3S HV: Add ICP real mode counters
  KVM: PPC: Book3S HV: Move virtual mode ICP functions to real-mode
  KVM: PPC: Book3S HV: Convert ICS mutex lock to spin lock
  KVM: PPC: Book3S HV: Add guest->host real mode completion counters
  KVM: PPC: Book3S HV: Add helpers for lock/unlock hpte
  ...

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The new Atmel MXT driver expects i2c client's address contain the
primary (main address) of the chip, and calculates the expected
bootloader address form the primary address. Unfortunately chrome_laptop
does probe the devices and if touchpad (or touchscreen, or both) comes
up in bootloader mode the i2c device gets instantiated with the
bootloader address which confuses the driver.

To work around this issue let's probe the primary address first. If the
device is not detected at the primary address we'll probe alternative
addresses as "dummy" devices. If any of them are found, destroy the
dummy client and instantiate client with proper name at primary address
still.
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Olof Johansson <olof@lixom.net>

Calling unlazy_walk() in walk_component() and do_last() when we find
a symlink that needs to be followed doesn't acquire a reference to vfsmount.
That's fine when the symlink is on the same vfsmount as the parent directory
(which is almost always the case), but it's not always true - one _can_
manage to bind a symlink on top of something.  And in such cases we end up
with excessive mntput().

Cc: stable@vger.kernel.org # since 2.6.39
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

I_DIO_WAKEUP is never directly used, but fix it up anyway.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

do_blockdev_direct_IO() increments and decrements the inode
->i_dio_count for each IO operation. It does this to protect against
truncate of a file. Block devices don't need this sort of protection.

For a capable multiqueue setup, this atomic int is the only shared
state between applications accessing the device for O_DIRECT, and it
presents a scaling wall for that. In my testing, as much as 30% of
system time is spent incrementing and decrementing this value. A mixed
read/write workload improved from ~2.5M IOPS to ~9.6M IOPS, with
better latencies too. Before:

clat percentiles (usec):
 |  1.00th=[   33],  5.00th=[   34], 10.00th=[   34], 20.00th=[   34],
 | 30.00th=[   34], 40.00th=[   34], 50.00th=[   35], 60.00th=[   35],
 | 70.00th=[   35], 80.00th=[   35], 90.00th=[   37], 95.00th=[   80],
 | 99.00th=[   98], 99.50th=[  151], 99.90th=[  155], 99.95th=[  155],
 | 99.99th=[  165]

After:

clat percentiles (usec):
 |  1.00th=[   95],  5.00th=[  108], 10.00th=[  129], 20.00th=[  149],
 | 30.00th=[  155], 40.00th=[  161], 50.00th=[  167], 60.00th=[  171],
 | 70.00th=[  177], 80.00th=[  185], 90.00th=[  201], 95.00th=[  270],
 | 99.00th=[  390], 99.50th=[  398], 99.90th=[  418], 99.95th=[  422],
 | 99.99th=[  438]

In other setups, Robert Elliott reported seeing good performance
improvements:

https://lkml.org/lkml/2015/4/3/557

The more applications accessing the device, the worse it gets.

Add a new direct-io flags, DIO_SKIP_DIO_COUNT, which tells
do_blockdev_direct_IO() that it need not worry about incrementing
or decrementing the inode i_dio_count for this caller.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Elliott, Robert (Server Storage) <elliott@hp.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Al Viro's IOV changes broke 9p readdir() because the new code
didn't abort the read when it returned nothing. The original
code checked if the combined error/length was <= 0 but in the
new code that accidentally got changed to just an error check.

Add back the return from the function when nothing is read.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Fixes: e1200fe6 ("9p: switch p9_client_read() to passing struct iov_iter *")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>