Merge reason: it's stable so lets push it upstream.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

The commit f4780ca0 moves
swiotlb initialization before dma32_free_bootmem(). It's
supposed to fix a bug that the commit
75f1cdf1 introduced, we
initialize SWIOTLB right after dma32_free_bootmem so we wrongly
steal memory area allocated for GART with broken BIOS earlier.

However, the above commit introduced another problem, which
likely breaks machines with huge amount of memory. Such a box
use the majority of DMA32_ZONE so there is no memory for
swiotlb.

With this patch, the x86 IOMMU initialization sequence are:

1. We set swiotlb to 1 in the case of (max_pfn > MAX_DMA32_PFN
   && !no_iommu). If swiotlb usage is forced by the boot option,
   we go to the step 3 and finish (we don't try to detect IOMMUs).

2. We call the detection functions of all the IOMMUs. The
   detection function sets x86_init.iommu.iommu_init to the IOMMU
   initialization function (so we can avoid calling the
   initialization functions of all the IOMMUs needlessly).

3. We initialize swiotlb (and set dma_ops to swiotlb_dma_ops) if
   swiotlb is set to 1.

4. If the IOMMU initialization function doesn't need swiotlb
   (e.g. the initialization is sucessful) then sets swiotlb to zero.

5. If we find that swiotlb is set to zero, we free swiotlb
   resource.
Reported-by: Yinghai Lu <yinghai@kernel.org>
Reported-by: Roland Dreier <rdreier@cisco.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
LKML-Reference: <20091215204729A.fujita.tomonori@lab.ntt.co.jp>
Tested-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

This adds a new category of symbols to the relocs program: symbols
which are known to be relative, even though the linker emits them as
absolute; this is the case for symbols that live in the linker script,
which currently applies to _end.

Unfortunately the previous workaround of putting _end in its own empty
section was defeated by newer binutils, which remove empty sections
completely.

This patch also changes the symbol matching to use regular expressions
instead of hardcoded C for specific patterns.

This is a decidedly non-minimal patch: a modified version of the
relocs program is used as part of the Syslinux build, and this 	is
basically a backport to Linux of some of those changes; they have
thus been well tested.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
LKML-Reference: <4AF86211.3070103@zytor.com>
Acked-by: Michal Marek <mmarek@suse.cz>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>

The MSR driver would compute the values for cpu and c at declaration,
and then again in the body of the function.  This isn't merely
redundant, but unsafe, since cpu might not refer to a valid CPU at
that point.

Remove the unnecessary and dangerous references in the declarations.
This code now matches the equivalent code in the CPUID driver.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

It looks better to have a common function. No change in functionality.
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
LKML-Reference: <4B25FDDC.407@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>

Add check if APIC is not disabled since thermal
monitoring depends on it. As only apic gets disabled
we should not try to install "thermal monitor" vector,
print out that thermal monitoring is enabled and etc...

Note that "Intel Correct Machine Check Interrupts" already
has such a check.

Also I decided to not add cpu_has_apic check into
mcheck_intel_therm_init since even if it'll call apic_read on
disabled apic -- it's safe here and allow us to save a few code
bytes.
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
LKML-Reference: <4B25FDC2.3020401@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

This fixes the following breakage of the commit
75f1cdf1:

- GART systems that don't AGP with broken BIOS and more than 4GB
  memory are forced to use swiotlb. They can allocate aperture by
  hand and use GART.

- GART systems without GAP must disable GART on shutdown.

- swiotlb usage is forced by the boot option,
  gart_iommu_hole_init() is not called, so we disable GART
  early_gart_iommu_check().
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
LKML-Reference: <1260759135-6450-3-git-send-email-fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

The commit 75f1cdf1 introduced a
bug that we initialize SWIOTLB right after dma32_free_bootmem so
we wrongly steal memory area allocated for GART with broken BIOS
earlier.

This moves swiotlb initialization before dma32_free_bootmem().
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: yinghai@kernel.org
LKML-Reference: <1260759135-6450-2-git-send-email-fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Stephen Rothwell reported these warnings:

 arch/x86/mm/mmio-mod.c: In function 'print_pte':
 arch/x86/mm/mmio-mod.c:100: warning: too many arguments for format
 arch/x86/mm/mmio-mod.c:106: warning: too many arguments for format

The 'fmt' was left out accidentally.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Joe Perches <joe@perches.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus <torvalds@linux-foundation.org>
LKML-Reference: <1260775443.18538.16.camel@Joe-Laptop.home>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

The reason of removal, "replaced by allowdac and no dac
combination" is incorrect. There is no way to do the same thing
with "allowdac" and "nodac" combination.

The usedac option enables us to stop via_no_dac() setting
forbid_dac to 1. That is, someone who uses VIA bridges can use
DAC with this option even if some of VIA bridges seem to be
broken about DAC.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: WANG Cong <amwang@redhat.com>
Cc: gcosta@redhat.com
LKML-Reference: <20091214104423X.fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Interrupt vector 0xec has been doubly defined in irq_vectors.h

It seems arbitrary whether LOCAL_PENDING_VECTOR or
UV_BAU_MESSAGE is the higher number.  As long as they are
unique. If they are not unique we'll hit a BUG in
alloc_system_vector().
Signed-off-by: Cliff Wickman <cpw@sgi.com>
Cc: <stable@kernel.org>
LKML-Reference: <E1NJ9Pe-0004P7-0Q@eag09.americas.sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

In nvram_write, first of all, correctly handle the case where the file
pointer is already beyond the end; we should return EOF in that case.

Second, make the logic a bit more explicit so that gcc can statically
prove that the copy_from_user() is safe.  Once the condition of the
beyond-end filepointer is eliminated, the copy is safe but gcc can't
prove it, causing build failures for i386 allyesconfig.

Third, eliminate the entirely superfluous variable "len", and just use
the passed-in variable "count" instead.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Wim Van Sebroeck <wim@iguana.be>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <tip-*@git.kernel.org>

Slightly adjust the logic for determining the size of the
copy_form_user() in do_pages_stat(); with this change, gcc can see
that the copying is safe.

Without this, we get a build error for i386 allyesconfig:

/home/hpa/kernel/linux-2.6-tip.urgent/arch/x86/include/asm/uaccess_32.h:213:
error: call to ‘copy_from_user_overflow’ declared with attribute
error: copy_from_user() buffer size is not provably correct

Unlike an earlier patch from Arjan, this doesn't introduce new
variables; merely reshuffles the compare so that gcc can see that an
overflow cannot happen.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Brice Goglin <Brice.Goglin@inria.fr>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
LKML-Reference: <20090926205406.30d55b08@infradead.org>

When there are a large number of processors in a system, there
is an excessive amount of messages sent to the system console.
It's estimated that with 4096 processors in a system, and the
console baudrate set to 56K, the startup messages will take
about 84 minutes to clear the serial port.

This set of patches limits the number of repetitious messages
which contain no additional information.  Much of this information
is obtainable from the /proc and /sysfs.   Some of the messages
are also sent to the kernel log buffer as KERN_DEBUG messages so
dmesg can be used to examine more closely any details specific to
a problem.

The new cpu bootup sequence for system_state == SYSTEM_BOOTING:

Booting Node   0, Processors  #1 #2 #3 #4 #5 #6 #7 Ok.
Booting Node   1, Processors  #8 #9 #10 #11 #12 #13 #14 #15 Ok.
...
Booting Node   3, Processors  #56 #57 #58 #59 #60 #61 #62 #63 Ok.
Brought up 64 CPUs

After the system is running, a single line boot message is displayed
when CPU's are hotplugged on:

    Booting Node %d Processor %d APIC 0x%x

Status of the following lines:

    CPU: Physical Processor ID:		printed once (for boot cpu)
    CPU: Processor Core ID:		printed once (for boot cpu)
    CPU: Hyper-Threading is disabled	printed once (for boot cpu)
    CPU: Thermal monitoring enabled	printed once (for boot cpu)
    CPU %d/0x%x -> Node %d:		removed
    CPU %d is now offline:		only if system_state == RUNNING
    Initializing CPU#%d:		KERN_DEBUG
Signed-off-by: Mike Travis <travis@sgi.com>
LKML-Reference: <4B219E28.8080601@sgi.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Print only once that the system is supporting x2apic mode.
Signed-off-by: Mike Travis <travis@sgi.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
LKML-Reference: <4B226E92.5080904@sgi.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Add documentation for kernel/bootloader_type and
kernel/bootloader_version to sysctl/kernel.txt.  This should really
have been done a long time ago.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Shen Feng <shen@cn.fujitsu.com>

The current rd/wrmsr_on_cpus helpers assume that the supplied
cpumasks are contiguous. However, there are machines out there
like some K8 multinode Opterons which have a non-contiguous core
enumeration on each node (e.g. cores 0,2 on node 0 instead of 0,1), see
http://www.gossamer-threads.com/lists/linux/kernel/1160268.

This patch fixes out-of-bounds writes (see URL above) by adding per-CPU
msr structs which are used on the respective cores.

Additionally, two helpers, msrs_{alloc,free}, are provided for use by
the callers of the MSR accessors.

Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Mauro Carvalho Chehab <mchehab@redhat.com>
Cc: Aristeu Rozanski <aris@redhat.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Doug Thompson <dougthompson@xmission.com>
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
LKML-Reference: <20091211171440.GD31998@aftab>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Jens found the following crash/regression:

[    0.000000] found SMP MP-table at [ffff8800000fdd80] fdd80
[    0.000000] Kernel panic - not syncing: Overlapping early reservations 12-f011 MP-table mpc to 0-fff BIOS data page

and

[    0.000000] Kernel panic - not syncing: Overlapping early reservations 12-f011 MP-table mpc to 6000-7fff TRAMPOLINE

and bisected it to b24c2a92 ("x86: Move find_smp_config()
earlier and avoid bootmem usage").

It turns out the BIOS is using the first 64k for mptable,
without reserving it.

So try to find good range for the real-mode trampoline instead of
hard coding it, in case some bios tries to use that range for sth.
Reported-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Tested-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
LKML-Reference: <4B21630A.6000308@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

* 'drm-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6: (189 commits)
  drm/radeon/kms: fix warning about cur_placement being uninitialised.
  drm/ttm: Print debug information on memory manager when eviction fails
  drm: Add memory manager debug function
  drm/radeon/kms: restore surface registers on resume.
  drm/radeon/kms/r600/r700: fallback gracefully on ucode failure
  drm/ttm: Initialize eviction placement in case the driver callback doesn't
  drm/radeon/kms: cleanup structure and module if initialization fails
  drm/radeon/kms: actualy set the eviction placements we choose
  drm/radeon/kms: Fix NULL ptr dereference
  drm/radeon/kms/avivo: add support for new pll selection algo
  drm/radeon/kms/avivo: fix some bugs in the display bandwidth setup
  drm/radeon/kms: fix return value from fence function.
  drm/radeon: Remove tests for -ERESTART from the TTM code.
  drm/ttm: Have the TTM code return -ERESTARTSYS instead of -ERESTART.
  drm/radeon/kms: Convert radeon to new TTM validation API (V2)
  drm/ttm: Rework validation & memory space allocation (V3)
  drm: Add search/get functions to get a block in a specific range
  drm/radeon/kms: fix avivo tiling regression since radeon object rework
  drm/i915: Remove a debugging printk from hangcheck
  drm/radeon/kms: make sure i2c id matches
  ...

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/bp/bp: (21 commits)
  amd64_edac: bump driver version
  amd64_edac: fix use-uninitialised bug
  amd64_edac: correct sys address to chip select mapping
  amd64_edac: add a leaner syndrome decoding algorithm
  amd64_edac: remove early hw support check
  amd64_edac: detect DDR3 memory type
  edac: add memory types strings for debugging
  edac, mce: update AMD F10h revD check
  amd64_edac: remove unneeded extract_error_address wrapper
  amd64_edac: rename StinkyIdentifier
  amd64_edac: remove superfluous dbg printk
  amd64_edac: enhance address to DRAM bank mapping
  amd64_edac: cleanup f10_early_channel_count
  amd64_edac: dump DIMM sizes on K8 too
  amd64_edac: cleanup rest of amd64_dump_misc_regs
  amd64_edac: cleanup DRAM cfg low debug output
  amd64_edac: wrap-up pci config read error handling
  amd64_edac: unify MCGCTL ECC switching
  cpumask: use modern cpumask style in drivers/edac/amd64_edac.c
  amd64_edac: make DRAM regions output more human-readable
  ...

* 'for-linus' of git://gitorious.org/linux-omap-dss2/linux:
  MAINTAINERS: Add OMAP2/3 DSS and OMAPFB maintainer
  OMAP: SDP: Enable DSS2 for OMAP3 SDP board
  OMAP: DSS2: Taal DSI command mode panel driver
  OMAP: DSS2: Add generic and Sharp panel drivers
  OMAP: DSS2: omapfb driver
  OMAP: DSS2: DSI driver
  OMAP: DSS2: SDI driver
  OMAP: DSS2: RFBI driver
  OMAP: DSS2: Video encoder driver
  OMAP: DSS2: DPI driver
  OMAP: DSS2: DISPC
  OMAP: DSS2: Add more core files
  OMAP: DSS2: Display Subsystem Driver core
  OMAP: DSS2: Documentation for DSS2
  OMAP: Add support for VRFB rotation engine
  OMAP: Add VRAM manager
  OMAP: OMAPFB: add omapdss device
  OMAP: OMAPFB: split omapfb.h
  OMAP2: Add funcs for writing SMS_ROT_* registers

The per_cpu cpuid4_info shared_map can contain stale data when CPUs are added
and removed.

The stale data can lead to a NULL pointer derefernce panic on a remove of a
CPU that has had siblings previously removed.

This patch resolves the panic by verifying a cpu is actually online before
adding it to the shared_cpu_map, only examining cpus that are part of
the same lower level cache, and by updating other siblings lowest level cache
maps when a cpu is added.
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
LKML-Reference: <20091209183336.17855.98708.sendpatchset@prarit.bos.redhat.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Signed-off-by: Brian Gerst <brgerst@gmail.com>
LKML-Reference: <1260380084-3707-6-git-send-email-brgerst@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Signed-off-by: Brian Gerst <brgerst@gmail.com>
LKML-Reference: <1260380084-3707-5-git-send-email-brgerst@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

The arg should be in %eax, but that is clobbered by the return value
of clone.  The function pointer can be in any register.  Also, don't
push args onto the stack, since regparm(3) is the normal calling
convention now.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
LKML-Reference: <1260380084-3707-4-git-send-email-brgerst@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Use user_mode() instead of a magic value for sp to determine when returning
to kernel mode.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
LKML-Reference: <1260380084-3707-3-git-send-email-brgerst@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Prepare for merging with 32-bit.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
LKML-Reference: <1260380084-3707-2-git-send-email-brgerst@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: Add debugobjects support

* 'bugfix' of git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen:
  xen: try harder to balloon up under memory pressure.
  Xen balloon: fix totalram_pages counting.
  xen: explicitly create/destroy stop_machine workqueues outside suspend/resume region.
  xen: improve error handling in do_suspend.
  xen: don't leak IRQs over suspend/resume.
  xen: call clock resume notifier on all CPUs
  xen: use iret for return from 64b kernel to 32b usermode
  xen: don't call dpm_resume_noirq() with interrupts disabled.
  xen: register runstate info for boot CPU early
  xen: register runstate on secondary CPUs
  xen: register timer interrupt with IRQF_TIMER
  xen: correctly restore pfn_to_mfn_list_list after resume
  xen: restore runstate_info even if !have_vcpu_info_placement
  xen: re-register runstate area earlier on resume.
  xen: wait up to 5 minutes for device connetion
  xen: improvement to wait_for_devices()
  xen: fix is_disconnected_device/exists_disconnected_device
  xen/xenbus: make DEVICE_ATTR()s static

* 'xen/fbdev' of git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen:
  xen pvfb: Inhibit VM_IO flag to be set on vmalloc-ed framebuffers.
  fb-defio: Inhibit VM_IO flag to be set on vmalloc-ed framebuffers.
  fb-defio: If FBINFO_VIRTFB is defined, do not set VM_IO flag.
  Fix toogle whether xenbus driver should be built as module or part of kernel.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/teigland/dlm:
  dlm: always use GFP_NOFS

* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (47 commits)
  ext4: Fix potential fiemap deadlock (mmap_sem vs. i_data_sem)
  ext4: Do not override ext2 or ext3 if built they are built as modules
  jbd2: Export jbd2_log_start_commit to fix ext4 build
  ext4: Fix insufficient checks in EXT4_IOC_MOVE_EXT
  ext4: Wait for proper transaction commit on fsync
  ext4: fix incorrect block reservation on quota transfer.
  ext4: quota macros cleanup
  ext4: ext4_get_reserved_space() must return bytes instead of blocks
  ext4: remove blocks from inode prealloc list on failure
  ext4: wait for log to commit when umounting
  ext4: Avoid data / filesystem corruption when write fails to copy data
  ext4: Use ext4 file system driver for ext2/ext3 file system mounts
  ext4: Return the PTR_ERR of the correct pointer in setup_new_group_blocks()
  jbd2: Add ENOMEM checking in and for jbd2_journal_write_metadata_buffer()
  ext4: remove unused parameter wbc from __ext4_journalled_writepage()
  ext4: remove encountered_congestion trace
  ext4: move_extent_per_page() cleanup
  ext4: initialize moved_len before calling ext4_move_extents()
  ext4: Fix double-free of blocks with EXT4_IOC_MOVE_EXT
  ext4: use ext4_data_block_valid() in ext4_free_blocks()
  ...

* 'for-linus' of git://git.open-osd.org/linux-open-osd:
  exofs: Multi-device mirror support
  exofs: Move all operations to an io_engine
  exofs: move osd.c to ios.c
  exofs: statfs blocks is sectors not FS blocks
  exofs: Prints on mount and unmout
  exofs: refactor exofs_i_info initialization into common helper
  exofs: dbg-print less
  exofs: More sane debug print
  trivial: some small fixes in exofs documentation

* git://git.infradead.org/ubifs-2.6:
  UBIFS: fix return code in check_leaf
  UBI: flush wl before clearing update marker
  MAINTAINERS: change e-mail of Artem Bityutskiy
  UBIFS: remove manual O_SYNC handling
  UBIFS: support mounting of UBI volume character devices
  UBI: Add ubi_open_volume_path

This patch drops usage of floating point variable for 32bit build
Signed-off-by: David T. L. Wong <davidtlwong@gmail.com>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

Merge branch 'amd-iommu/fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/linux-2.6-iommu into x86/urgent

The device change notifier is initialized in the dma_ops
initialization path. But this path is never executed for
iommu=pt. Move the notifier initialization to IOMMU hardware
init code to fix this.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

The data structure changes to use dev->archdata.iommu field
broke the iommu=pt mode because in this case the
dev->archdata.iommu was left uninitialized. This moves the
inititalization of the devices into the main init function
and fixes the problem.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

This patch changes on-disk format, it is accompanied with a parallel
patch to mkfs.exofs that enables multi-device capabilities.

After this patch, old exofs will refuse to mount a new formatted FS and
new exofs will refuse an old format. This is done by moving the magic
field offset inside the FSCB. A new FSCB *version* field was added. In
the future, exofs will refuse to mount unmatched FSCB version. To
up-grade or down-grade an exofs one must use mkfs.exofs --upgrade option
before mounting.

Introduced, a new object that contains a *device-table*. This object
contains the default *data-map* and a linear array of devices
information, which identifies the devices used in the filesystem. This
object is only written to offline by mkfs.exofs. This is why it is kept
separate from the FSCB, since the later is written to while mounted.

Same partition number, same object number is used on all devices only
the device varies.

* define the new format, then load the device table on mount time make
  sure every thing is supported.

* Change I/O engine to now support Mirror IO, .i.e write same data
  to multiple devices, read from a random device to spread the
  read-load from multiple clients (TODO: stripe read)

Implementation notes:
 A few points introduced in previous patch should be mentioned here:

* Special care was made so absolutlly all operation that have any chance
  of failing are done before any osd-request is executed. This is to
  minimize the need for a data consistency recovery, to only real IO
  errors.

* Each IO state has a kref. It starts at 1, any osd-request executed
  will increment the kref, finally when all are executed the first ref
  is dropped. At IO-done, each request completion decrements the kref,
  the last one to return executes the internal _last_io() routine.
  _last_io() will call the registered io_state_done. On sync mode a
  caller does not supply a done method, indicating a synchronous
  request, the caller is put to sleep and a special io_state_done is
  registered that will awaken the caller. Though also in sync mode all
  operations are executed in parallel.
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>