These have been broken (returning "int") since the dawn of
time. But there were no users that needed the whole value
until commit
 424acaae
 rwsem: wake queued readers when writer blocks on active read lock

made this change:

-           (rwsem_atomic_update(0, sem) & RWSEM_ACTIVE_MASK))
-               /* Someone grabbed the sem already */
+           rwsem_atomic_update(0, sem) < RWSEM_WAITING_BIAS)
+               /* Someone grabbed the sem for write already */

RWSEM_ACTIVE_MASK is 0xffffffffL, so the old code only looked
at the low order 32-bits. The new code needs to see all 64 bits.
Signed-off-by: Tony Luck <tony.luck@intel.com>

* 'io_remap_pfn_range' of git://www.jni.nu/cris:
  CRIS: Define io_remap_pfn_range as remap_pfn_range

* git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-2.6-dm: (33 commits)
  dm mpath: support discard
  dm stripe: support discards
  dm: split discard requests on target boundaries
  dm stripe: optimize sector division
  dm stripe: move sector translation to a function
  dm: error return error for discards
  dm delay: support discard
  dm: zero silently drop discards
  dm: use dm_target_offset macro
  dm: factor out max_io_len_target_boundary
  dm: use common __issue_target_request for flush and discard support
  dm: linear support discard
  dm crypt: simplify crypt_ctr
  dm crypt: simplify crypt_config destruction logic
  dm: allow autoloading of dm mod
  dm: rename map_info flush_request to target_request_nr
  dm ioctl: refactor dm_table_complete
  dm snapshot: implement merge
  dm: do not initialise full request queue when bio based
  dm ioctl: make bio or request based device type immutable
  ...

* 'hwpoison' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6:
  hugetlb: add missing unlock in avoidcopy path in hugetlb_cow()
  hwpoison: rename CONFIG
  HWPOISON, hugetlb: support hwpoison injection for hugepage
  HWPOISON, hugetlb: detect hwpoison in hugetlb code
  HWPOISON, hugetlb: isolate corrupted hugepage
  HWPOISON, hugetlb: maintain mce_bad_pages in handling hugepage error
  HWPOISON, hugetlb: set/clear PG_hwpoison bits on hugepage
  HWPOISON, hugetlb: enable error handling path for hugepage
  hugetlb, rmap: add reverse mapping for hugepage
  hugetlb: move definition of is_vm_hugetlb_page() to hugepage_inline.h

Fix up trivial conflicts in mm/memory-failure.c

* 'for-linus' of git://neil.brown.name/md:
  Further tidyup of raid6 naming in lib/raid6
  Make lib/raid6/test build correctly.
  Rename raid6 files now they're in a 'raid6' directory.

* 'msm-core' of git://codeaurora.org/quic/kernel/dwalker/linux-msm:
  msm: mmc: Add msm prefix to platform data structure
  msm: trout: Remove extern declaration from source file
  arm: msm: Fix section mismatch in smd.c.
  arm: msm: trout add mmc support
  arm: msm: trout: add trout specific gpio interrupts
  arm: msm: remove unused #include <linux/version.h>

* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq:
  [CPUFREQ] add missing __percpu markup in pcc-cpufreq.c

* 'i2c-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jdelvare/staging:
  i2c: I2C bus multiplexer driver pca954x
  i2c: Multiplexed I2C bus core support
  i2c: Use a separate mutex for userspace client lists
  i2c: Make i2c_default_probe self-sufficient
  i2c: Drop dummy variable
  i2c: Move adapter locking helpers to i2c-core
  V4L/DVB: Use custom I2C probing function mechanism
  i2c: Add support for custom probe function
  i2c-dev: Use memdup_user
  i2c-dev: Remove unnecessary kmalloc casts

* 'params' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus: (22 commits)
  param: don't deref arg in __same_type() checks
  param: update drivers/acpi/debug.c to new scheme
  param: use module_param in drivers/message/fusion/mptbase.c
  ide: use module_param_named rather than module_param_call
  param: update drivers/char/ipmi/ipmi_watchdog.c to new scheme
  param: lock if_sdio's lbs_helper_name and lbs_fw_name against sysfs changes.
  param: lock myri10ge_fw_name against sysfs changes.
  param: simple locking for sysfs-writable charp parameters
  param: remove unnecessary writable charp
  param: add kerneldoc to moduleparam.h
  param: locking for kernel parameters
  param: make param sections const.
  param: use free hook for charp (fix leak of charp parameters)
  param: add a free hook to kernel_param_ops.
  param: silence .init.text references from param ops
  Add param ops struct for hvc_iucv driver.
  nfs: update for module_param_named API change
  AppArmor: update for module_param_named API change
  param: use ops in struct kernel_param, rather than get and set fns directly
  param: move the EXPORT_SYMBOL to after the definitions.
  ...

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/lrg/voltage-2.6: (22 commits)
  regulator: Remove default DEBUG define from TPS6586x
  regulator: tps6507x - add missing platform_set_drvdata in tps6507x_pmic_probe
  regulator: tps6586x - add regulator_unregister() in tps6586x_regulator_remove()
  mfd: max8998 - fix incorrect kfree(i2c) in i2c_driver probe callback handler
  regulator: lp3971 - remove unnecessary ret value checking in lp3971_i2c_write()
  regulator: max8660 - fix a memory leak in max8660_remove()
  regulator: max1586 - fix a memory leak in max1586_pmic_remove()
  regulator: Default GPIO controlled WM8994 regulators to disabled
  regulator: lp3971 - remove unnecessary ret value checking in lp3971_i2c_write()
  max8998: fix off-by-one value range checking
  regulator: tps6586x: fix millivolt return values and SM2 table
  regulator: tps6586x: add dependancy on MFD_TPS6585x
  regulator: add TPS6586X regulator driver
  regulator: MAX8998: set_voltage bugfix. ramp_up delay and min/max voltage
  regulator: add support for regulators on the ab8500 MFD
  ab8500-mfd: add regulator support to ab8500 mfd device
  tps65023: Allow registering similar TPS65021
  drivers: regulators: depend on MFD_MAX8998
  drivers: regulator: add Maxim 8998 driver
  ISL6271A voltage regulator support.
  ...

* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/sameo/mfd-2.6: (40 commits)
  mfd: Fix incorrect kfree(i2c) in wm8994-core i2c_driver probe
  mfd: Fix incorrect kfree(i2c) in wm831x-core i2c_driver probe
  mfd: Fix incorrect kfree(i2c) in tps6507x i2c_driver probe
  mfd: Add TPS6586x driver
  mfd: Use macros instead of some constant magic numbers for menelaus
  mfd: Fix menelaus mmc slot 2 misconfiguration
  mfd: Missing slab.h includes
  mfd: Fix wrong wm8350-core kfree in error path
  mfd: Fix wm8994_device_init() return value
  mfd: Avoid calling platform_device_put() twice in ucb1400 probe error path
  mfd: Annotate tc6387xb probe/remove routines with __devinit/__devexit
  mfd: Fix tc6387xb resource reclaim
  mfd: Fix wrong goto labels for tc6393xb error handling
  mfd: Get rid of now unused mc13783 private header
  hwmon: Don't access struct mc13783 directly from mc13783-adc
  mfd: New mc13783 function exposing flags
  mfd: Check jz4740-adc kmalloc() result
  mfd: Fix jz4740-adc resource reclaim in probe error path
  mfd: Add WM8321 support
  mfd: Add stmpe auto sleep feature
  ...

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6:
  ASoC: add AD1980 obsolete information
  ASoC: register cache should be 1 byte aligned for 1 byte long register
  ALSA: hda - Adding support for new IDT 92HD87XX codecs
  ASoC: Fix inverted mute controls for WM8580
  ALSA: HDA: Use model=auto for LG R510
  ALSA: hda - Update model entries in HD-Audio-Models.txt
  ALSA: hda: document VIA models
  ALSA: hda - patch_nvhdmi.c: Add missing codec IDs, unify names
  ALSA: hda - add support for Conexant CX20584
  ALSA: hda - New snd-hda-intel model/pin config for hp dv7-4000
  ALSA: hda - Fix missing stream for second ADC on Realtek ALC260 HDA codec
  ALSA: hda - Make converter setups sticky
  ALSA: hda - Add support for Acer ZGA ALC271 (1025:047c)
  sound/oss: Adjust confusing if indentation
  sound: oss: au1550_ac97.c removed duplicated #include
  ASoC: Fix for changed Eureka Kconfig symbol names

* git://git.infradead.org/battery-2.6:
  intel_mid_battery: Fix battery scaling
  intel_mid_battery: Fix the argument order to intel_scu_ipc_command
  olpc_battery: Fix build failure caused by sysfs changes
  Add s3c-adc-battery driver
  Intel MID platform battery driver

Fix up trivial conflicts (battery drivers added from different branches)
in drivers/power/{Kconfig,Makefile}

The current computation, introduced with f12a15be, of FSEC_PER_SEC using
the multiplication of (FSEC_PER_NSEC * NSEC_PER_SEC) is performed only
with 32bit integers on small machines, resulting in an overflow and a
*very* short intervals being programmed.  An interrupt storm follows.

Note that we also have to specify FSEC_PER_SEC as being long long to
overcome the same limitations.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The tv_nsec is a long and when added to the shifted interval it can wrap
and become negative which later causes looping problems in the
getrawmonotonic().  The edge case occurs when the system has slept for
a short period of time of ~2 seconds.

A trace printk of the values in this patch illustrate the problem:

ftrace time stamp: log
43.716079: logarithmic_accumulation: raw: 3d0913 tv_nsec d687faa
43.718513: logarithmic_accumulation: raw: 3d0913 tv_nsec da588bd
43.722161: logarithmic_accumulation: raw: 3d0913 tv_nsec de291d0
46.349925: logarithmic_accumulation: raw: 7a122600 tv_nsec e1f9ae3b
46.349930: logarithmic_accumulation: raw: 1e848980 tv_nsec 8831c0e3

The kernel starts looping at 46.349925 in the getrawmonotonic() due to
the negative value from adding the raw value to tv_nsec.

A simple solution is to accumulate into a u64, and then normalize it
to a timespec_t.
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
 [ Reworked variable names and simplified some of the code. - John ]
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Use no_printk() for disabled gdbstub debugging functions to maintain side
effect checking.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Add a dummy printk function for the maintenance of unused printks through gcc
format checking, and also so that side-effect checking is maintained too.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Don't try and #include <linux/slab.h> in lib/inflate.c from the bootloader code
as linux/slab.h hauls in function defs that aren't available in the bootloader
code and may also haul in conflicting functions.

To fix this, make the inclusion of linux/slab.h contingent on NO_INFLATE_MALLOC
as are the usages of kmalloc() and kfree().

In MN10300, this causes the following errors:

In file included from include/linux/string.h:21,
                 from include/linux/bitmap.h:8,
                 from include/linux/nodemask.h:93,
                 from include/linux/mmzone.h:16,
                 from include/linux/gfp.h:4,
                 from include/linux/slab.h:12,
                 from arch/mn10300/boot/compressed/../../../../lib/inflate.c:106,
                 from arch/mn10300/boot/compressed/misc.c:170:
/warthog/am33/linux-2.6-mn10300/arch/mn10300/include/asm/string.h:19: error: conflicting types for 'memset'
arch/mn10300/boot/compressed/misc.c:59: error: previous definition of 'memset' was here
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Permit .GCC-command-line sections in modules.  Otherwise modpost says things
like:

WARNING: drivers/mtd/chips/map_ram.o (.GCC-command-line): unexpected non-allocatable section.
Did you forget to use "ax"/"aw" in a .S file?
Note that for example <linux/init.h> contains
section definitions for use in .S files.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

With the newer compilers, size_t and ssize_t are expected to be (un)signed int
rather than (un)signed long.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

A change to the RTC routines in the MN10300 arch used set_rtc_mms() when it
meant set_rtc_mmss().  This results in an error due to a reference of an
undefined symbol.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

pcc_cpu_info is a percpu pointer but was missing __percpu markup.
Add it.
Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Dave Jones <davej@redhat.com>

* 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux-2.6:
  [IA64] Fix rwsem: RWSEM_WAITING_BIAS must not be unsigned.

* 'drm-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6: (55 commits)
  io-mapping: move asm include inside the config option
  vgaarb: drop vga.h include
  drm/radeon: Add probing of clocks from device-tree
  drm/radeon: drop old and broken mesa warning
  drm/radeon: Fix pci_map_page() error checking
  drm: Remove count_lock for calling lastclose() after 58474713 (v2)
  drm/radeon/kms: allow FG_ALPHA_VALUE on r5xx
  drm/radeon/kms: another r6xx/r7xx CS checker fix
  DRM: Replace kmalloc/memset combos with kzalloc
  drm: expand gamma_set
  drm/edid: Split mode lists out to their own header for readability
  drm/edid: Rewrite mode parse to use the generic detailed block walk
  drm/edid: Add detailed block walk for VTB extensions
  drm/edid: Add detailed block walk for CEA extensions
  drm: Remove unused fields from drm_display_info
  drm: Use ENOENT consistently for the error return for an unmatched handle.
  drm/radeon/kms: mark 3D power states as performance
  drm: Only set DPMS once on the CRTC not after every encoder.
  drm/radeon/kms: add additional quirk for Acer rv620 laptop
  drm: Propagate error code from fb_create()
  ...

Fix up trivial conflicts in drivers/gpu/drm/drm_edid.c

Some nice improvements were made to rwsem in commit:

 424acaae
 rwsem: wake queued readers when writer blocks on active read lock

but this change overlooked that ia64 had defined RWSEM_WAITING_BIAS
as an unsigned value, while the new code required a signed value (as
it is in every other architecture).

This fix suggested by the original patch author: Michel Lespinasse.
Signed-off-by: Tony Luck <tony.luck@intel.com>

* 'next-devicetree' of git://git.secretlab.ca/git/linux-2.6:
  mmc_spi: Fix unterminated of_match_table
  of/sparc: fix build regression from of_device changes
  of/device: Replace struct of_device with struct platform_device

* 'stable/xen-swiotlb-0.8.6' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen:
  x86: Detect whether we should use Xen SWIOTLB.
  pci-swiotlb-xen: Add glue code to setup dma_ops utilizing xen_swiotlb_* functions.
  swiotlb-xen: SWIOTLB library for Xen PV guest with PCI passthrough.
  xen/mmu: inhibit vmap aliases rather than trying to clear them out
  vmap: add flag to allow lazy unmap to be disabled at runtime
  xen: Add xen_create_contiguous_region
  xen: Rename the balloon lock
  xen: Allow unprivileged Xen domains to create iomap pages
  xen: use _PAGE_IOMAP in ioremap to do machine mappings

Fix up trivial conflicts (adding both xen swiotlb and xen pci platform
driver setup close to each other) in drivers/xen/{Kconfig,Makefile} and
include/xen/xen-ops.h

mspro_block_remove() is called from detect thread that first calls the
mspro_block_stop(), which stops the request queue.  If we call
del_gendisk() with the queue stopped we get a deadlock.
Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Cc: Alex Dubov <oakad@yahoo.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Otherwise lockdep complains.
Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Cc: Alex Dubov <oakad@yahoo.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

- Fix mmc_test_alloc_mem.

- Use nr_free_buffer_pages() instead of sysinfo.totalram to determine
  total lowmem pages.

- Change variables containing memory sizes to unsigned long.

- Limit maximum test area size to 128MiB because that is the maximum MMC
  high capacity erase size (the maxmium SD allocation unit size is just
  4MiB)
Signed-off-by: Adrian Hunter <adrian.hunter@nokia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mmc_test provides tests aimed at testing SD/MMC hosts.  This patch adds
performance tests.

It is advantageous to have performance tests in a kernel
module like mmc_test for the following reasons:
	- transfer times can be measured very accurately
	- arbitrarily large transfers are possible
	- the effect of contiguous vs scattered pages
	can be determined

The new tests are:

	23. Best-case read performance
	24. Best-case write performance
	25. Best-case read performance into scattered pages
	26. Best-case write performance from scattered pages
	27. Single read performance by transfer size
	28. Single write performance by transfer size
	29. Single trim performance by transfer size
	30. Consecutive read performance by transfer size
	31. Consecutive write performance by transfer size
	32. Consecutive trim performance by transfer size
Signed-off-by: Adrian Hunter <adrian.hunter@nokia.com>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Secure discard is implemented by Secure Trim if the discard is unaligned
or Secure Erase otherwise.
Signed-off-by: Adrian Hunter <adrian.hunter@nokia.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Cc: Kyungmin Park <kmpark@infradead.org>
Cc: Madhusudhan Chikkature <madhu.cr@ti.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ben Gardiner <bengardiner@nanometrics.ca>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Secure discard is the same as discard except that all copies of the
discarded sectors (perhaps created by garbage collection) must also be
erased.
Signed-off-by: Adrian Hunter <adrian.hunter@nokia.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Cc: Kyungmin Park <kmpark@infradead.org>
Cc: Madhusudhan Chikkature <madhu.cr@ti.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ben Gardiner <bengardiner@nanometrics.ca>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Disable the data (busy) timeout for erases and set the MMC_CAP_ERASE
capability.
Signed-off-by: Adrian Hunter <adrian.hunter@nokia.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Cc: Kyungmin Park <kmpark@infradead.org>
Cc: Madhusudhan Chikkature <madhu.cr@ti.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ben Gardiner <bengardiner@nanometrics.ca>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Enable MMC to service discard requests.  In the case of SD and MMC cards
that do not support trim, discards become erases.  In the case of cards
(MMC) that only allow erases in multiples of erase group size, round to
the nearest completely discarded erase group.
Signed-off-by: Adrian Hunter <adrian.hunter@nokia.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Cc: Kyungmin Park <kmpark@infradead.org>
Cc: Madhusudhan Chikkature <madhu.cr@ti.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ben Gardiner <bengardiner@nanometrics.ca>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

SD/MMC cards tend to support an erase operation.  In addition, eMMC v4.4
cards can support secure erase, trim and secure trim operations that are
all variants of the basic erase command.

SD/MMC device attributes "erase_size" and "preferred_erase_size" have been
added.

"erase_size" is the minimum size, in bytes, of an erase operation.  For
MMC, "erase_size" is the erase group size reported by the card.  Note that
"erase_size" does not apply to trim or secure trim operations where the
minimum size is always one 512 byte sector.  For SD, "erase_size" is 512
if the card is block-addressed, 0 otherwise.

SD/MMC cards can erase an arbitrarily large area up to and
including the whole card.  When erasing a large area it may
be desirable to do it in smaller chunks for three reasons:

    1. A single erase command will make all other I/O on the card
       wait.  This is not a problem if the whole card is being erased, but
       erasing one partition will make I/O for another partition on the
       same card wait for the duration of the erase - which could be a
       several minutes.

    2. To be able to inform the user of erase progress.

    3. The erase timeout becomes too large to be very useful.
       Because the erase timeout contains a margin which is multiplied by
       the size of the erase area, the value can end up being several
       minutes for large areas.

"erase_size" is not the most efficient unit to erase (especially for SD
where it is just one sector), hence "preferred_erase_size" provides a good
chunk size for erasing large areas.

For MMC, "preferred_erase_size" is the high-capacity erase size if a card
specifies one, otherwise it is based on the capacity of the card.

For SD, "preferred_erase_size" is the allocation unit size specified by
the card.

"preferred_erase_size" is in bytes.
Signed-off-by: Adrian Hunter <adrian.hunter@nokia.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Cc: Kyungmin Park <kmpark@infradead.org>
Cc: Madhusudhan Chikkature <madhu.cr@ti.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ben Gardiner <bengardiner@nanometrics.ca>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit 83ba7b07 ("writeback: simplify the write back thread queue")
broke writeback_in_progress() as in that commit we started to remove work
items from the list at the moment we start working on them and not at the
moment they are finished.  Thus if the flusher thread was doing some work
but there was no other work queued, writeback_in_progress() returned
false.  This could in particular cause unnecessary queueing of background
writeback from balance_dirty_pages() or writeout work from
writeback_sb_if_idle().

This patch fixes the problem by introducing a bit in the bdi state which
indicates that the flusher thread is processing some work and uses this
bit for writeback_in_progress() test.

NOTE: Both callsites of writeback_in_progress() (namely,
writeback_inodes_sb_if_idle() and balance_dirty_pages()) would actually
need a different information than what writeback_in_progress() provides.
They would need to know whether *the kind of writeback they are going to
submit* is already queued.  But this information isn't that simple to
provide so let's fix writeback_in_progress() for the time being.
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Acked-by: Jens Axboe <jaxboe@fusionio.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Unify the logic for kupdate and non-kupdate cases.  There won't be
starvation because the inodes requeued into b_more_io will later be
spliced _after_ the remaining inodes in b_io, hence won't stand in the way
of other inodes in the next run.

It avoids unnecessary redirty_tail() calls, hence the update of
i_dirtied_when.  The timestamp update is undesirable because it could
later delay the inode's periodic writeback, or may exclude the inode from
the data integrity sync operation (which checks timestamp to avoid extra
work and livelock).

===
How the redirty_tail() comes about:

It was a long story..  This redirty_tail() was introduced with
wbc.more_io.  The initial patch for more_io actually does not have the
redirty_tail(), and when it's merged, several 100% iowait bug reports
arised:

reiserfs:
        http://lkml.org/lkml/2007/10/23/93

jfs:
        commit 29a424f2
        JFS: clear PAGECACHE_TAG_DIRTY for no-write pages

ext2:
        http://www.spinics.net/linux/lists/linux-ext4/msg04762.html

They are all old bugs hidden in various filesystems that become "visible"
with the more_io patch.  At the time, the ext2 bug is thought to be
"trivial", so not fixed.  Instead the following updated more_io patch with
redirty_tail() is merged:

	http://www.spinics.net/linux/lists/linux-ext4/msg04507.html

This will in general prevent 100% on ext2 and possibly other unknown FS bugs.
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Martin Bligh <mbligh@google.com>
Cc: Michael Rubin <mrubin@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This was not a bug, since b_io is empty for kupdate writeback.  The next
patch will do requeue_io() for non-kupdate writeback, so let's fix it.
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Martin Bligh <mbligh@google.com>
Cc: Michael Rubin <mrubin@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Avoid delaying writeback for an expire inode with lots of dirty pages, but
no active dirtier at the moment.  Previously we only do that for the
kupdate case.

Any filesystem that does delayed allocation or unwritten extent conversion
after IO completion will cause this - for example, XFS.
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Acked-by: Jan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>