The query callback should only update the hw_state, see the comment in
net/rfkill/core.c in rfkill_set_block, which is its only caller.

rfkill_set_block will modify the sw_state directly after calling query so
calling set_sw_state is an expensive NOP.
Signed-off-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NMatthew Garrett <matthew.garrett@nebula.com>

Signed-off-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NMatthew Garrett <matthew.garrett@nebula.com>

To ensure we don't enter any hw-switch related code paths on machines without
a hw-switch.
Signed-off-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NMatthew Garrett <matthew.garrett@nebula.com>

The rfkill functionality was removed from the dell-laptop driver because it
was causing problems on various non Latitude models, and the blacklist kept
growing and growing. In the thread discussing this Dell mentioned that they
only QA the rfkill acpi interface on Latitudes and indeed there have been
no blacklist entries for Latitudes.

Note that the blacklist contained no Vostros either, and most Vostros have
a hardware switch too, so we could consider supporting Vostros with a
hardware switch too.
Signed-off-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NMatthew Garrett <matthew.garrett@nebula.com>

Without rfkill functionality in dell-laptop I have the following problems:
-If the hardware radio switch is set to disable the radio, then userspace
 will still think it can use wireless and bluetooth.
-The wwan / 3g modem cannot be soft blocked without the dell-laptop rfkill
 functionality

I know the rfkill functionality was removed from the dell-laptop driver because
it caused more problems then it fixed, and the blacklist for it was growing out
of control.

But in the thread discussing this Dell mentioned that they only QA the rfkill
acpi interface on Latitudes and indeed there have been no blacklist entries
for Latitudes. Therefor I would like to bring the rfkill functionality back
only for Latitudes. This patch is a straight-forward revert. The next patch
in this set will drop the blacklist and replace it with a Latitude check.

This reverts commit a6c2390c.

Conflicts:
	drivers/platform/x86/dell-laptop.c
Signed-off-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NMatthew Garrett <matthew.garrett@nebula.com>

Pull powerpc LE updates from Ben Herrenschmidt:
 "With my previous pull request I mentioned some remaining Little Endian
  patches, notably support for our new ABI, which I was sitting on
  making sure it was all finalized.

  The toolchain folks confirmed it now, the new ABI is stable and merged
  with gcc, so we are all good.  Oh and we actually missed the actual
  Kconfig switch for LE so here it is, along with a couple more bug
  fixes.

  I have more fixes but not related to LE so I'll send them as a
  separate pull request tomorrow, let's get this one out of the way.

  Note that this supports running user space binaries using the new ABI,
  but the kernel itself still needs to be built with the old one.  We'll
  bring fixes for that after -rc1.

  Here's Anton log that goes with this series:

     This patch series adds support for the new ABI, LPAR support for
     H_SET_MODE and finally adds a kconfig option and defconfig.

     ABIv2 support was recently committed to binutils and gcc, and should
     be merged into glibc soon.  There are a number of very nice
     improvements including the removal of function descriptors.  Rusty's
     kernel patches allow binaries of either ABI to work, easing the
     transition"

* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc:
  powerpc: Wrong DWARF CFI in the kernel vdso for little-endian / ELFv2
  powerpc: Add pseries_le_defconfig
  powerpc: Add CONFIG_CPU_LITTLE_ENDIAN kernel config option.
  powerpc: Don't use ELFv2 ABI to build the kernel
  powerpc: ELF2 binaries signal handling
  powerpc: ELF2 binaries launched directly.
  powerpc: Set eflags correctly for ELF ABIv2 core dumps.
  powerpc: Add TIF_ELF2ABI flag.
  pseries: Add H_SET_MODE to change exception endianness
  powerpc/pseries: Fix endian issues in pseries EEH code

Pull alpha updates from Matt Turner:
 "It contains a few fixes and some work from Richard to make alpha
  emulation under QEMU much more usable"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mattst88/alpha:
  alpha: Prevent a NULL ptr dereference in csum_partial_copy.
  alpha: perf: fix out-of-bounds array access triggered from raw event
  alpha: Use qemu+cserve provided high-res clock and alarm.
  alpha: Switch to GENERIC_CLOCKEVENTS
  alpha: Enable the rpcc clocksource for single processor
  alpha: Reorganize rtc handling
  alpha: Primitive support for CPU power down.
  alpha: Allow HZ to be configured
  alpha: Notice if we're being run under QEMU
  alpha: Eliminate compiler warning from memset macro

Pull parisc fixes from Helge Deller:
 - revert an access_ok() patch which broke 32bit userspace on 64bit
   kernels
 - avoid a gcc miscompilation in two internal pa_memcpy() functions by
   not inlining those
 - do not export the definition of SOCK_NONBLOCK via uapi header (fixes
   build of audit package)
 - depending on the fault type we now correctly report either SIGBUS or
   SIGSEGV
 - a small fix to not compare a size_t variable for < 0

* 'parisc-3.13' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
  parisc: size_t is unsigned, so comparison size < 0 doesn't make sense.
  parisc: improve SIGBUS/SIGSEGV error reporting
  parisc: break out SOCK_NONBLOCK define to own asm header file
  parisc: do not inline pa_memcpy() internal functions
  Revert "parisc: implement full version of access_ok()"

Pull AVR32 updates from Hans-Christian Egtvedt.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/egtvedt/linux-avr32:
  avr32: uapi: be sure of "_UAPI" prefix for all guard macros
  avr32: add kprobe_ctlblk memory struct
  avr32: fix out-of-range jump in large kernels
  avr32: setup crt for early panic()

Pull squashfs updates from Phillip Lougher:
 "These patches optionally improve the multi-threading peformance of
  Squashfs by adding parallel decompression, and direct decompression
  into the page cache, eliminating an intermediate buffer (removing
  memcpy overhead and lock contention)"

* tag 'squashfs-updates' of git://git.kernel.org/pub/scm/linux/kernel/git/pkl/squashfs-next:
  Squashfs: Check stream is not NULL in decompressor_multi.c
  Squashfs: Directly decompress into the page cache for file data
  Squashfs: Restructure squashfs_readpage()
  Squashfs: Generalise paging handling in the decompressors
  Squashfs: add multi-threaded decompression using percpu variable
  squashfs: Enhance parallel I/O
  Squashfs: Refactor decompressor interface and code

This reverts commit ea1e7ed3.

Al points out that while the commit *does* actually create a separate
slab for the page->ptl allocation, that slab is never actually used, and
the code continues to use kmalloc/kfree.

Damien Wyart points out that the original patch did have the conversion
to use kmem_cache_alloc/free, so it got lost somewhere on its way to me.

Revert the half-arsed attempt that didn't do anything.  If we really do
want the special slab (remember: this is all relevant just for debug
builds, so it's not necessarily all that critical) we might as well redo
the patch fully.
Reported-by: NAl Viro <viro@zeniv.linux.org.uk>
Acked-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Kirill A Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Pull vfs bits and pieces from Al Viro:
 "Assorted bits that got missed in the first pull request + fixes for a
  couple of coredump regressions"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  fold try_to_ascend() into the sole remaining caller
  dcache.c: get rid of pointless macros
  take read_seqbegin_or_lock() and friends to seqlock.h
  consolidate simple ->d_delete() instances
  gfs2: endianness misannotations
  dump_emit(): use __kernel_write(), not vfs_write()
  dump_align(): fix the dumb braino

Note that pmds[i] is simply uninitialized at that point...

Granted, it's very hard to hit (you need split page locks *and*
kmalloc(sizeof(spinlock_t), GFP_KERNEL) failing), but the code is
obviously bogus.

Introduced by commit 09ef4939 ("x86: add missed
pgtable_pmd_page_ctor/dtor calls for preallocated pmds")
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

I've finally tracked down why my CR signal-unwind test case still
fails on little-endian.  The problem turned to be that the kernel
installs a signal trampoline in the vDSO, and provides a DWARF CFI
record for that trampoline.  This CFI describes the save location
for CR:

  rsave (70, 38*RSIZE + (RSIZE - CRSIZE))

which is correct for big-endian, but points to the wrong word on
little-endian.   This is wrong no matter which ABI.

In addition, for the ELFv2 ABI, we should not only provide a CFI
record for register 70 (cr2), but for all CR fields separately.
Strictly speaking, I guess this would mean providing two separate
vDSO images, one for ELFv1 processes and one for ELFv2 processes (or
maybe playing some tricks with conditional DWARF expressions).
However, having CFI records for the other CR fields in ELFv1 is not
actually wrong, they just will be ignored.   So it seems the simplest
fix would be just to always provide CFI for all the fields.
Signed-off-by: NUlrich Weigand <Ulrich.Weigand@de.ibm.com>
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

With the little endian support merged, we can add the
CONFIG_CPU_LITTLE_ENDIAN kernel config option.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

The kernel doesn't build correctly using the ELFv2 ABI.  This patch
ensures that the ELFv1 ABI is used when building a kernel with an
ELFv2 enabled compiler.
Signed-off-by: NAlistair Popple <alistair@popple.id.au>
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

For the ELFv2 ABI, the hander is the entry point, not a function descriptor.
We also need to set up r12, and fortunately the fast_exception_return
exit path restores r12 for us so nothing else is required.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

No function descriptor, but we set r12 up and set TIF_RESTOREALL as it
normally isn't restored on return from syscall.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

We leave it at zero (though it could be 1) for old tasks.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Little endian ppc64 is getting an exciting new ABI.  This is reflected
by the bottom two bits of e_flags in the ELF header:

	0 == legacy binaries (v1 ABI)
	1 == binaries using the old ABI (compiled with a new toolchain)
	2 == binaries using the new ABI.

We store this in a thread flag, because we need to set it in core
dumps and for signal delivery.  Our chief concern is that it doesn't
use function descriptors.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

On little endian builds call H_SET_MODE so exceptions have the
correct endianness. We need to reset the endian during kexec
so do that in the MMU hashtable clear callback.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Pull more ACPI and power management updates from Rafael Wysocki:

 - ACPI-based device hotplug fixes for issues introduced recently and a
   fix for an older error code path bug in the ACPI PCI host bridge
   driver

 - Fix for recently broken OMAP cpufreq build from Viresh Kumar

 - Fix for a recent hibernation regression related to s2disk

 - Fix for a locking-related regression in the ACPI EC driver from
   Puneet Kumar

 - System suspend error code path fix related to runtime PM and runtime
   PM documentation update from Ulf Hansson

 - cpufreq's conservative governor fix from Xiaoguang Chen

 - New processor IDs for intel_idle and turbostat and removal of an
   obsolete Kconfig option from Len Brown

 - New device IDs for the ACPI LPSS (Low-Power Subsystem) driver and
   ACPI-based PCI hotplug (ACPIPHP) cleanup from Mika Westerberg

 - Removal of several ACPI video DMI blacklist entries that are not
   necessary any more from Aaron Lu

 - Rework of the ACPI companion representation in struct device and code
   cleanup related to that change from Rafael J Wysocki, Lan Tianyu and
   Jarkko Nikula

 - Fixes for assigning names to ACPI-enumerated I2C and SPI devices from
   Jarkko Nikula

* tag 'pm+acpi-2-3.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (24 commits)
  PCI / hotplug / ACPI: Drop unused acpiphp_debug declaration
  ACPI / scan: Set flags.match_driver in acpi_bus_scan_fixed()
  ACPI / PCI root: Clear driver_data before failing enumeration
  ACPI / hotplug: Fix PCI host bridge hot removal
  ACPI / hotplug: Fix acpi_bus_get_device() return value check
  cpufreq: governor: Remove fossil comment in the cpufreq_governor_dbs()
  ACPI / video: clean up DMI table for initial black screen problem
  ACPI / EC: Ensure lock is acquired before accessing ec struct members
  PM / Hibernate: Do not crash kernel in free_basic_memory_bitmaps()
  ACPI / AC: Remove struct acpi_device pointer from struct acpi_ac
  spi: Use stable dev_name for ACPI enumerated SPI slaves
  i2c: Use stable dev_name for ACPI enumerated I2C slaves
  ACPI: Provide acpi_dev_name accessor for struct acpi_device device name
  ACPI / bind: Use (put|get)_device() on ACPI device objects too
  ACPI: Eliminate the DEVICE_ACPI_HANDLE() macro
  ACPI / driver core: Store an ACPI device pointer in struct acpi_dev_node
  cpufreq: OMAP: Fix compilation error 'r & ret undeclared'
  PM / Runtime: Fix error path for prepare
  PM / Runtime: Update documentation around probe|remove|suspend
  cpufreq: conservative: set requested_freq to policy max when it is over policy max
  ...

Pull slave-dmaengine changes from Vinod Koul:
 "This brings for slave dmaengine:

   - Change dma notification flag to DMA_COMPLETE from DMA_SUCCESS as
     dmaengine can only transfer and not verify validaty of dma
     transfers

   - Bunch of fixes across drivers:

      - cppi41 driver fixes from Daniel

      - 8 channel freescale dma engine support and updated bindings from
        Hongbo

      - msx-dma fixes and cleanup by Markus

   - DMAengine updates from Dan:

      - Bartlomiej and Dan finalized a rework of the dma address unmap
        implementation.

      - In the course of testing 1/ a collection of enhancements to
        dmatest fell out.  Notably basic performance statistics, and
        fixed / enhanced test control through new module parameters
        'run', 'wait', 'noverify', and 'verbose'.  Thanks to Andriy and
        Linus [Walleij] for their review.

      - Testing the raid related corner cases of 1/ triggered bugs in
        the recently added 16-source operation support in the ioatdma
        driver.

      - Some minor fixes / cleanups to mv_xor and ioatdma"

* 'next' of git://git.infradead.org/users/vkoul/slave-dma: (99 commits)
  dma: mv_xor: Fix mis-usage of mmio 'base' and 'high_base' registers
  dma: mv_xor: Remove unneeded NULL address check
  ioat: fix ioat3_irq_reinit
  ioat: kill msix_single_vector support
  raid6test: add new corner case for ioatdma driver
  ioatdma: clean up sed pool kmem_cache
  ioatdma: fix selection of 16 vs 8 source path
  ioatdma: fix sed pool selection
  ioatdma: Fix bug in selftest after removal of DMA_MEMSET.
  dmatest: verbose mode
  dmatest: convert to dmaengine_unmap_data
  dmatest: add a 'wait' parameter
  dmatest: add basic performance metrics
  dmatest: add support for skipping verification and random data setup
  dmatest: use pseudo random numbers
  dmatest: support xor-only, or pq-only channels in tests
  dmatest: restore ability to start test at module load and init
  dmatest: cleanup redundant "dmatest: " prefixes
  dmatest: replace stored results mechanism, with uniform messages
  Revert "dmatest: append verify result to results"
  ...

Pull block IO fixes from Jens Axboe:
 "Normally I'd defer my initial for-linus pull request until after the
  merge window, but a race was uncovered in the virtio-blk conversion to
  blk-mq that could cause hangs.  So here's a small collection of fixes
  for you to pull:

   - The fix for the virtio-blk IO hang reported by Dave Chinner, from
     Shaohua and myself.

   - Add the Insert blktrace event for blk-mq.  This makes 'btt' happy
     when it is doing it's state transition analysis.

   - Ensure that blk-mq has disk/partition stats enabled by default,
     instead of making it opt-in.

   - A fix for __bio_add_page() and large sector counts"

* 'for-linus' of git://git.kernel.dk/linux-block:
  blk-mq: add blktrace insert event trace
  virtio-blk: virtqueue_kick() must be ordered with other virtqueue operations
  blk-mq: ensure that we set REQ_IO_STAT so diskstats work
  bio: fix argument of __bio_add_page() for max_sectors > 0xffff

Pull md update from Neil Brown:
 "Mostly optimisations and obscure bug fixes.
   - raid5 gets less lock contention
   - raid1 gets less contention between normal-io and resync-io during
     resync"

* tag 'md/3.13' of git://neil.brown.name/md:
  md/raid5: Use conf->device_lock protect changing of multi-thread resources.
  md/raid5: Before freeing old multi-thread worker, it should flush them.
  md/raid5: For stripe with R5_ReadNoMerge, we replace REQ_FLUSH with REQ_NOMERGE.
  UAPI: include <asm/byteorder.h> in linux/raid/md_p.h
  raid1: Rewrite the implementation of iobarrier.
  raid1: Add some macros to make code clearly.
  raid1: Replace raise_barrier/lower_barrier with freeze_array/unfreeze_array when reconfiguring the array.
  raid1: Add a field array_frozen to indicate whether raid in freeze state.
  md: Convert use of typedef ctl_table to struct ctl_table
  md/raid5: avoid deadlock when raid5 array has unack badblocks during md_stop_writes.
  md: use MD_RECOVERY_INTR instead of kthread_should_stop in resync thread.
  md: fix some places where mddev_lock return value is not checked.
  raid5: Retry R5_ReadNoMerge flag when hit a read error.
  raid5: relieve lock contention in get_active_stripe()
  raid5: relieve lock contention in get_active_stripe()
  wait: add wait_event_cmd()
  md/raid5.c: add proper locking to error path of raid5_start_reshape.
  md: fix calculation of stacking limits on level change.
  raid5: Use slow_path to release stripe when mddev->thread is null

For all uapi headers, need use "_UAPI" prefix for its guard macro
(which will be stripped by "scripts/headers_installer.sh").

Also remove redundant files (bitsperlong.h, errno.h, fcntl.h, ioctl.h,
ioctls.h, ipcbuf.h, kvm_para.h, mman.h, poll.h, resource.h, siginfo.h,
statfs.h, and unistd.h) which are already in Kbuild.

Also be sure that all "#endif" only have one empty line above, and each
file has guard macro.
Signed-off-by: NChen Gang <gang.chen@asianux.com>
Signed-off-by: NHans-Christian Egtvedt <hegtvedt@cisco.com>

This re-enables kprobes on AVR32 architecture.
Signed-off-by: NEirik Aanonsen <eaa@wprmedical.com>
Signed-off-by: NHans-Christian Egtvedt <egtvedt@samfundet.no>

This patch fixes following error (for big kernels):

---8<---
arch/avr32/boot/u-boot/head.o: In function `no_tag_table':
(.init.text+0x44): relocation truncated to fit: R_AVR32_22H_PCREL against symbol `panic' defined in .text.unlikely section in kernel/built-in.o
arch/avr32/kernel/built-in.o: In function `bad_return':
(.ex.text+0x236): relocation truncated to fit: R_AVR32_22H_PCREL against symbol `panic' defined in .text.unlikely section in kernel/built-in.o
--->8---

It comes up when the kernel increases and 'panic()' is too far away to fit in
the +/- 2MiB range. Which in turn issues from the 21-bit displacement in
'br{cond4}' mnemonic which is one of the two ways to do jumps (rjmp has just
10-bit displacement and therefore a way smaller range). This fact was stated
before in 8d29b7b9.
One solution to solve this is to add a local storage for the symbol address
and just load the $pc with that value.
Signed-off-by: NAndreas Bießmann <andreas@biessmann.de>
Acked-by: NHans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: stable@vger.kernel.org

Before the CRT was (fully) set up in kernel_entry (bss cleared before in
_start, but also not before jump to panic() in no_tag_table case).

This patch fixes this up to have a fully working CRT when branching to panic()
in no_tag_table.
Signed-off-by: NAndreas Bießmann <andreas@biessmann.de>
Acked-by: NHans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: stable@vger.kernel.org

Fix static checker complaint that stream is not checked in
squashfs_decompressor_destroy().
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NPhillip Lougher <phillip@squashfs.org.uk>
Reviewed-by: NMinchan Kim <minchan@kernel.org>

This introduces an implementation of squashfs_readpage_block()
that directly decompresses into the page cache.

This uses the previously added page handler abstraction to push
down the necessary kmap_atomic/kunmap_atomic operations on the
page cache buffers into the decompressors.  This enables
direct copying into the page cache without using the slow
kmap/kunmap calls.

The code detects when multiple threads are racing in
squashfs_readpage() to decompress the same block, and avoids
this regression by falling back to using an intermediate
buffer.

This patch enhances the performance of Squashfs significantly
when multiple processes are accessing the filesystem simultaneously
because it not only reduces memcopying, but it more importantly
eliminates the lock contention on the intermediate buffer.

Using single-thread decompression.

        dd if=file1 of=/dev/null bs=4096 &
        dd if=file2 of=/dev/null bs=4096 &
        dd if=file3 of=/dev/null bs=4096 &
        dd if=file4 of=/dev/null bs=4096

Before:

629145600 bytes (629 MB) copied, 45.8046 s, 13.7 MB/s

After:

629145600 bytes (629 MB) copied, 9.29414 s, 67.7 MB/s
Signed-off-by: NPhillip Lougher <phillip@squashfs.org.uk>
Reviewed-by: NMinchan Kim <minchan@kernel.org>

Restructure squashfs_readpage() splitting it into separate
functions for datablocks, fragments and sparse blocks.

Move the memcpying (from squashfs cache entry) implementation of
squashfs_readpage_block into file_cache.c

This allows different implementations to be supported.
Signed-off-by: NPhillip Lougher <phillip@squashfs.org.uk>
Reviewed-by: NMinchan Kim <minchan@kernel.org>

Further generalise the decompressors by adding a page handler
abstraction.  This adds helpers to allow the decompressors
to access and process the output buffers in an implementation
independant manner.

This allows different types of output buffer to be passed
to the decompressors, with the implementation specific
aspects handled at decompression time, but without the
knowledge being held in the decompressor wrapper code.

This will allow the decompressors to handle Squashfs
cache buffers, and page cache pages.

This patch adds the abstraction and an implementation for
the caches.
Signed-off-by: NPhillip Lougher <phillip@squashfs.org.uk>
Reviewed-by: NMinchan Kim <minchan@kernel.org>

Add a multi-threaded decompression implementation which uses
percpu variables.

Using percpu variables has advantages and disadvantages over
implementations which do not use percpu variables.

Advantages:
  * the nature of percpu variables ensures decompression is
    load-balanced across the multiple cores.
  * simplicity.

Disadvantages: it limits decompression to one thread per core.
Signed-off-by: NPhillip Lougher <phillip@squashfs.org.uk>

Now squashfs have used for only one stream buffer for decompression
so it hurts parallel read performance so this patch supports
multiple decompressor to enhance performance parallel I/O.

Four 1G file dd read on KVM machine which has 2 CPU and 4G memory.

dd if=test/test1.dat of=/dev/null &
dd if=test/test2.dat of=/dev/null &
dd if=test/test3.dat of=/dev/null &
dd if=test/test4.dat of=/dev/null &

old : 1m39s -> new : 9s

* From v1
  * Change comp_strm with decomp_strm - Phillip
  * Change/add comments - Phillip
Signed-off-by: NMinchan Kim <minchan@kernel.org>
Signed-off-by: NPhillip Lougher <phillip@squashfs.org.uk>

The decompressor interface and code was written from
the point of view of single-threaded operation.  In doing
so it mixed a lot of single-threaded implementation specific
aspects into the decompressor code and elsewhere which makes it
difficult to seamlessly support multiple different decompressor
implementations.

This patch does the following:

1.  It removes compressor_options parsing from the decompressor
    init() function.  This allows the decompressor init() function
    to be dynamically called to instantiate multiple decompressors,
    without the compressor options needing to be read and parsed each
    time.

2.  It moves threading and all sleeping operations out of the
    decompressors.  In doing so, it makes the decompressors
    non-blocking wrappers which only deal with interfacing with
    the decompressor implementation.

3. It splits decompressor.[ch] into decompressor generic functions
   in decompressor.[ch], and moves the single threaded
   decompressor implementation into decompressor_single.c.

The result of this patch is Squashfs should now be able to
support multiple decompressors by adding new decompressor_xxx.c
files with specialised implementations of the functions in
decompressor_single.c
Signed-off-by: NPhillip Lougher <phillip@squashfs.org.uk>
Reviewed-by: NMinchan Kim <minchan@kernel.org>

We need it to make 'btt' from blktrace happy, otherwise
we are missing one state transition.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

It isn't safe to call it without holding the vblk->vq_lock.
Reported-by: NDave Chinner <david@fromorbit.com>
Signed-off-by: NShaohua Li <shli@fusionio.com>

Fixed another condition of virtqueue_kick() not holding the lock.
Signed-off-by: NJens Axboe <axboe@kernel.dk>