Make __get_user_pages return -EHWPOISON for HWPOISON page only if
FOLL_HWPOISON is specified.  With this patch, the interested callers
can distinguish HWPOISON pages from general FAULT pages, while other
callers will still get -EFAULT for all these pages, so the user space
interface need not to be changed.

This feature is needed by KVM, where UCR MCE should be relayed to
guest for HWPOISON page, while instruction emulation and MMIO will be
tried for general FAULT page.

The idea comes from Andrew Morton.
Signed-off-by: NHuang Ying <ying.huang@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

In most cases, get_user_pages and get_user_pages_fast should be used
to pin user pages in memory.  But sometimes, some special flags except
FOLL_GET, FOLL_WRITE and FOLL_FORCE are needed, for example in
following patch, KVM needs FOLL_HWPOISON.  To support these users,
__get_user_pages is exported directly.

There are some symbol name conflicts in infiniband driver, fixed them too.
Signed-off-by: NHuang Ying <ying.huang@intel.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Michel Lespinasse <walken@google.com>
CC: Roland Dreier <roland@kernel.org>
CC: Ralph Campbell <infinipath@qlogic.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

A correction to Intel cpu model CPUID data (patch queued)
caused winxp to BSOD when booted with a Penryn model.
This was traced to the CPUID "model" field correction from
6 -> 23 (as is proper for a Penryn class of cpu).  Only in
this case does the problem surface.

The cause for this failure is winxp accessing the BBL_CR_CTL3
MSR which is unsupported by current kvm, appears to be a
legacy MSR not fully characterized yet existing in current
silicon, and is apparently carried forward in MSR space to
accommodate vintage code as here.  It is not yet conclusive
whether this MSR implements any of its legacy functionality
or is just an ornamental dud for compatibility.  While I
found no silicon version specific documentation link to
this MSR, a general description exists in Intel's developer's
reference which agrees with the functional behavior of
other bootloader/kernel code I've examined accessing
BBL_CR_CTL3.  Regrettably winxp appears to be setting bit #19
called out as "reserved" in the above document.

So to minimally accommodate this MSR, kvm msr get will provide
the equivalent mock data and kvm msr write will simply toss the
guest passed data without interpretation.  While this treatment
of BBL_CR_CTL3 addresses the immediate problem, the approach may
be modified pending clarification from Intel.
Signed-off-by: Njohn cooper <john.cooper@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Now, we have 'vcpu->mode' to judge whether need to send ipi to other
cpus, this way is very exact, so checking request bit is needless,
then we can drop the spinlock let it's collateral
Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Currently we keep track of only two states: guest mode and host
mode.  This patch adds an "exiting guest mode" state that tells
us that an IPI will happen soon, so unless we need to wait for the
IPI, we can avoid it completely.

Also
1: No need atomically to read/write ->mode in vcpu's thread

2: reorganize struct kvm_vcpu to make ->mode and ->requests
   in the same cache line explicitly
Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Get rid of this warning:

  CC      arch/s390/kvm/../../../virt/kvm/kvm_main.o
arch/s390/kvm/../../../virt/kvm/kvm_main.c:596:12: warning: 'kvm_create_dirty_bitmap' defined but not used

The only caller of the function is within a !CONFIG_S390 section, so add the
same ifdef around kvm_create_dirty_bitmap() as well.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

This case is a pure user space error we do not need to record. Moreover,
it can be misused to flood the kernel log. Remove it.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Fix:

[ 1001.499596] ===================================================
[ 1001.499599] [ INFO: suspicious rcu_dereference_check() usage. ]
[ 1001.499601] ---------------------------------------------------
[ 1001.499604] include/linux/kvm_host.h:301 invoked rcu_dereference_check() without protection!
	......
[ 1001.499636] Pid: 6035, comm: qemu-system-x86 Not tainted 2.6.37-rc6+ #62
[ 1001.499638] Call Trace:
[ 1001.499644]  [] lockdep_rcu_dereference+0x9d/0xa5
[ 1001.499653]  [] gfn_to_memslot+0x8d/0xc8 [kvm]
[ 1001.499661]  [] gfn_to_hva+0x16/0x3f [kvm]
[ 1001.499669]  [] kvm_read_guest_page+0x1e/0x5e [kvm]
[ 1001.499681]  [] kvm_read_guest_page_mmu+0x53/0x5e [kvm]
[ 1001.499699]  [] load_pdptrs+0x3f/0x9c [kvm]
[ 1001.499705]  [] ? vmx_set_cr0+0x507/0x517 [kvm_intel]
[ 1001.499717]  [] kvm_arch_vcpu_ioctl_set_sregs+0x1f3/0x3c0 [kvm]
[ 1001.499727]  [] kvm_vcpu_ioctl+0x6a5/0xbc5 [kvm]
Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Instead of exchanging the guest and host rcx, have separate storage
for each.  This allows us to avoid using the xchg instruction, which
is is a little slower than normal operations.
Signed-off-by: NAvi Kivity <avi@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Change

  push top-of-stack
  pop guest-rcx
  pop dummy

to

  pop guest-rcx

which is the same thing, only simpler.
Signed-off-by: NAvi Kivity <avi@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

On some CPUs, a ple_gap of 41 is simply insufficient to ever trigger
PLE exits, even with the minimalistic PLE test from kvm-unit-tests.

http://git.kernel.org/?p=virt/kvm/kvm-unit-tests.git;a=commitdiff;h=eda71b28fa122203e316483b35f37aaacd42f545

For example, the Xeon X5670 CPU needs a ple_gap of at least 48 in
order to get pause loop exits:

# modprobe kvm_intel ple_gap=47
# taskset 1 /usr/local/bin/qemu-system-x86_64 \
  -device testdev,chardev=log -chardev stdio,id=log \
  -kernel x86/vmexit.flat -append ple-round-robin -smp 2
VNC server running on `::1:5900'
enabling apic
enabling apic
ple-round-robin 58298446
# rmmod kvm_intel
# modprobe kvm_intel ple_gap=48
# taskset 1 /usr/local/bin/qemu-system-x86_64 \
   -device testdev,chardev=log -chardev stdio,id=log \
   -kernel x86/vmexit.flat -append ple-round-robin -smp 2
VNC server running on `::1:5900'
enabling apic
enabling apic
ple-round-robin 36616

Increase the ple_gap to 128 to be on the safe side.
Signed-off-by: NRik van Riel <riel@redhat.com>
Acked-by: NZhai, Edwin <edwin.zhai@intel.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

This patch adds the necessary code to run perf-kvm on AMD
machines.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

When emulating real mode, we fake some state:

 - tr.base points to a fake vm86 tss
 - segment registers are made to conform to vm86 restrictions

change vmx_get_segment() not to expose this fake state to userspace;
instead, return the original state.
Signed-off-by: NAvi Kivity <avi@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

When emulating real mode we play with tr hidden state, but leave
tr.selector alone.  That works well, except for save/restore, since
loading TR writes it to the hidden state in vmx->rmode.

Fix by also saving and restoring the tr selector; this makes things
more consistent and allows migration to work during the early
boot stages of Windows XP.
Signed-off-by: NAvi Kivity <avi@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Previously SPRGs 4-7 were improperly read and written in
kvm_arch_vcpu_ioctl_get_regs() and kvm_arch_vcpu_ioctl_set_regs();
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NPeter Tyser <ptyser@xes-inc.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

WARNING: arch/x86/built-in.o(.text+0x1bb74): Section mismatch in reference from the function kvm_guest_cpu_online() to the function .cpuinit.text:kvm_guest_cpu_init()
The function kvm_guest_cpu_online() references
the function __cpuinit kvm_guest_cpu_init().
This is often because kvm_guest_cpu_online lacks a __cpuinit
annotation or the annotation of kvm_guest_cpu_init is wrong.

This patch fixes the warning.

Tested with linux-next (next-20101231)
Signed-off-by: NSedat Dilek <sedat.dilek@gmail.com>
Acked-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Instead, drop large mappings, which were the reason we dropped shadow.
Signed-off-by: NAvi Kivity <avi@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

* 'mnt_devname' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6:
  vfs: bury ->get_sb()
  nfs: switch NFS from ->get_sb() to ->mount()
  nfs: stop mangling ->mnt_devname on NFS
  vfs: new superblock methods to override /proc/*/mount{s,info}
  nfs: nfs_do_{ref,sub}mount() superblock argument is redundant
  nfs: make nfs_path() work without vfsmount
  nfs: store devname at disconnected NFS roots
  nfs: propagate devname to nfs{,4}_get_root()

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k:
  m68k/block: amiflop - Remove superfluous amiga_chip_alloc() cast
  m68k/atari: ARAnyM - Add support for network access
  m68k/atari: ARAnyM - Add support for console access
  m68k/atari: ARAnyM - Add support for block access
  m68k/atari: Initial ARAnyM support
  m68k: Kconfig - Remove unneeded "default n"
  m68k: Makefiles - Change to new flags variables
  m68k/amiga: Reclaim Chip RAM for PPC exception handlers
  m68k: Allow all kernel traps to be handled via exception fixups
  m68k: Use base_trap_init() to initialize vectors
  m68k: Add helper function handle_kernel_fault()

* 'remove' of master.kernel.org:/home/rmk/linux-2.6-arm:
  ARM: 6629/2: aaec2000: remove support for mach-aaec2000
  ARM: lh7a40x: remove unmaintained platform support

Fix up trivial conflicts in
 - arch/arm/mach-{aaec2000,lh7a40x}/include/mach/memory.h (removed)
 - drivers/usb/gadget/Kconfig (USB_[GADGET_]LH7A40X removed, others added)

* 'for-linus' of master.kernel.org:/home/rmk/linux-2.6-arm: (91 commits)
  ARM: 6806/1: irq: introduce entry and exit functions for chained handlers
  ARM: 6781/1: Thumb-2: Work around buggy Thumb-2 short branch relocations in gas
  ARM: 6747/1: P2V: Thumb2 support
  ARM: 6798/1: aout-core: zero thread debug registers in a.out core dump
  ARM: 6796/1: Footbridge: Fix I/O mappings for NOMMU mode
  ARM: 6784/1: errata: no automatic Store Buffer drain on Cortex-A9
  ARM: 6772/1: errata: possible fault MMU translations following an ASID switch
  ARM: 6776/1: mach-ux500: activate fix for errata 753970
  ARM: 6794/1: SPEAr: Append UL to device address macros.
  ARM: 6793/1: SPEAr: Remove unused *_SIZE macros from spear*.h files
  ARM: 6792/1: SPEAr: Replace SIZE macro's with SZ_4K macros
  ARM: 6791/1: SPEAr3xx: Declare device structures after shirq code
  ARM: 6790/1: SPEAr: Clock Framework: Rename usbd clock and align apb_clk entry
  ARM: 6789/1: SPEAr3xx: Rename sdio to sdhci
  ARM: 6788/1: SPEAr: Include mach/hardware.h instead of mach/spear.h
  ARM: 6787/1: SPEAr: Reorder #includes in .h & .c files.
  ARM: 6681/1: SPEAr: add debugfs support to clk API
  ARM: 6703/1: SPEAr: update clk API support
  ARM: 6679/1: SPEAr: make clk API functions more generic
  ARM: 6737/1: SPEAr: formalized timer support
  ...

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu: (41 commits)
  m68knommu: external interrupt support to ColdFire intc-simr controller
  m68knommu: external interrupt support to ColdFire intc-2 controller
  m68knommu: remove ColdFire CLOCK_DIV config option
  m68knommu: fix gpio warnings for ColdFire 5407 targets
  m68knommu: fix gpio warnings for ColdFire 532x targets
  m68knommu: fix gpio warnings for ColdFire 5307 targets
  m68knommu: fix gpio warnings for ColdFire 527x targets
  m68knommu: fix gpio warnings for ColdFire 5272 targets
  m68knommu: fix gpio warnings for ColdFire 5249 targets
  m68knommu: fix gpio warnings for ColdFire 523x targets
  m68knommu: fix gpio warnings for ColdFire 520x targets
  m68knommu: fix gpio warnings for ColdFire 5206e targets
  m68knommu: fix gpio warnings for ColdFire 5206 targets
  m68knommu: fixing compiler warnings
  m68knommu: limit interrupts supported by ColdFire intc-simr driver
  m68knommu: move some init code out of unmask routine for ColdFire intc-2
  m68knommu: limit interrupts supported by ColdFire intc-2 driver
  m68knommu: add basic support for the ColdFire based FireBee board
  m68knommu: make ColdFire internal peripheral region configurable
  m68knommu: clean up definitions of ColdFire peripheral base registers
  ...

* 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux-2.6:
  [IA64] tioca: Fix assignment from incompatible pointer warnings
  [IA64] mca.c: Fix cast from integer to pointer warning
  [IA64] setup.c Typo fix "Architechtuallly"
  [IA64] Add CONFIG_MISC_DEVICES=y to configs that need it.
  [IA64] disable interrupts at end of ia64_mca_cpe_int_handler()
  [IA64] Add DMA_ERROR_CODE define.
  pstore: fix build warning for unused return value from sysfs_create_file
  pstore: X86 platform interface using ACPI/APEI/ERST
  pstore: new filesystem interface to platform persistent storage

* 'devicetree/next' of git://git.secretlab.ca/git/linux-2.6: (21 commits)
  tty: serial: altera_jtaguart: Add device tree support
  tty: serial: altera_uart: Add devicetree support
  dt: eliminate of_platform_driver shim code
  dt: Eliminate of_platform_{,un}register_driver
  dt/serial: Eliminate users of of_platform_{,un}register_driver
  dt/usb: Eliminate users of of_platform_{,un}register_driver
  dt/video: Eliminate users of of_platform_{,un}register_driver
  dt/net: Eliminate users of of_platform_{,un}register_driver
  dt/sound: Eliminate users of of_platform_{,un}register_driver
  dt/spi: Eliminate users of of_platform_{,un}register_driver
  dt: uartlite: merge platform and of_platform driver bindings
  dt: xilinx_hwicap: merge platform and of_platform driver bindings
  ipmi: convert OF driver to platform driver
  leds/leds-gpio: merge platform_driver with of_platform_driver
  dt/sparc: Eliminate users of of_platform_{,un}register_driver
  dt/powerpc: Eliminate users of of_platform_{,un}register_driver
  dt/powerpc: move of_bus_type infrastructure to ibmebus
  drivercore/dt: add a match table pointer to struct device
  dt: Typo fix.
  altera_ps2: Add devicetree support
  ...

* 'config' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl:
  BKL: That's all, folks
  fs/locks.c: Remove stale FIXME left over from BKL conversion
  ipx: remove the BKL
  appletalk: remove the BKL
  x25: remove the BKL
  ufs: remove the BKL
  hpfs: remove the BKL
  drivers: remove extraneous includes of smp_lock.h
  tracing: don't trace the BKL
  adfs: remove the big kernel lock

Conflicts:
	arch/arm/kernel/module.c
	arch/arm/mach-s5pv210/sleep.S

Conflicts:
	arch/arm/include/asm/cacheflush.h
	arch/arm/include/asm/proc-fns.h
	arch/arm/mm/Kconfig

Conflicts:
	arch/arm/Kconfig

Merge branches 'at91', 'ep93xx', 'errata', 'footbridge', 'fncpy', 'gemini', 'irqdata', 'pm', 'sh', 'smp', 'spear', 'ux500' and 'via' into devel

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6: (1480 commits)
  bonding: enable netpoll without checking link status
  xfrm: Refcount destination entry on xfrm_lookup
  net: introduce rx_handler results and logic around that
  bonding: get rid of IFF_SLAVE_INACTIVE netdev->priv_flag
  bonding: wrap slave state work
  net: get rid of multiple bond-related netdevice->priv_flags
  bonding: register slave pointer for rx_handler
  be2net: Bump up the version number
  be2net: Copyright notice change. Update to Emulex instead of ServerEngines
  e1000e: fix kconfig for crc32 dependency
  netfilter ebtables: fix xt_AUDIT to work with ebtables
  xen network backend driver
  bonding: Improve syslog message at device creation time
  bonding: Call netif_carrier_off after register_netdevice
  bonding: Incorrect TX queue offset
  net_sched: fix ip_tos2prio
  xfrm: fix __xfrm_route_forward()
  be2net: Fix UDP packet detected status in RX compl
  Phonet: fix aligned-mode pipe socket buffer header reserve
  netxen: support for GbE port settings
  ...

Fix up conflicts in drivers/staging/brcm80211/brcmsmac/wl_mac80211.c
with the staging updates.

* 'staging-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging-2.6: (961 commits)
  staging: hv: fix memory leaks
  staging: hv: Remove NULL check before kfree
  Staging: hv: Get rid of vmbus_child_dev_add()
  Staging: hv: Change the signature for vmbus_child_device_register()
  Staging: hv: Get rid of vmbus_cleanup() function
  Staging: hv: Get rid of vmbus_dev_rm() function
  Staging: hv: Change the signature for vmbus_on_isr()
  Staging: hv: Eliminate vmbus_event_dpc()
  Staging: hv: Get rid of the function vmbus_msg_dpc()
  Staging: hv: Change the signature for vmbus_cleanup()
  Staging: hv: Simplify root device management
  staging: rtl8192e: Don't copy dev pointer to skb
  staging: rtl8192e: Pass priv to cmdpkt functions
  staging: rtl8192e: Pass priv to firmware download functions
  staging: rtl8192e: Pass priv to rtl8192_interrupt
  staging: rtl8192e: Pass rtl8192_priv to dm functions
  staging: rtl8192e: Pass ieee80211_device to callbacks
  staging: rtl8192e: Pass ieee80211_device to callbacks
  staging: rtl8192e: Pass ieee80211_device to callbacks
  staging: rtl8192e: Pass ieee80211_device to callbacks
  ...

* 'tty-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6: (76 commits)
  pch_uart: reference clock on CM-iTC
  pch_phub: add new device ML7213
  n_gsm: fix UIH control byte : P bit should be 0
  n_gsm: add a documentation
  serial: msm_serial_hs: Add MSM high speed UART driver
  tty_audit: fix tty_audit_add_data live lock on audit disabled
  tty: move cd1865.h to drivers/staging/tty/
  Staging: tty: fix build with epca.c driver
  pcmcia: synclink_cs: fix prototype for mgslpc_ioctl()
  Staging: generic_serial: fix double locking bug
  nozomi: don't use flush_scheduled_work()
  tty/serial: Relax the device_type restriction from of_serial
  MAINTAINERS: Update HVC file patterns
  tty: phase out of ioctl file pointer for tty3270 as well
  tty: forgot to remove ipwireless from drivers/char/pcmcia/Makefile
  pch_uart: Fix DMA channel miss-setting issue.
  pch_uart: fix exclusive access issue
  pch_uart: fix auto flow control miss-setting issue
  pch_uart: fix uart clock setting issue
  pch_uart : Use dev_xxx not pr_xxx
  ...

Fix up trivial conflicts in drivers/misc/pch_phub.c (same patch applied
twice, then changes to the same area in one branch)

Merge branch 'driver-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core-2.6

* 'driver-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core-2.6: (50 commits)
  printk: do not mangle valid userspace syslog prefixes
  efivars: Add Documentation
  efivars: Expose efivars functionality to external drivers.
  efivars: Parameterize operations.
  efivars: Split out variable registration
  efivars: parameterize efivars
  efivars: Make efivars bin_attributes dynamic
  efivars: move efivars globals into struct efivars
  drivers:misc: ti-st: fix debugging code
  kref: Fix typo in kref documentation
  UIO: add PRUSS UIO driver support
  Fix spelling mistakes in Documentation/zh_CN/SubmittingPatches
  firmware: Fix unaligned memory accesses in dmi-sysfs
  firmware: Add documentation for /sys/firmware/dmi
  firmware: Expose DMI type 15 System Event Log
  firmware: Break out system_event_log in dmi-sysfs
  firmware: Basic dmi-sysfs support
  firmware: Add DMI entry types to the headers
  Driver core: convert platform_{get,set}_drvdata to static inline functions
  Translate linux-2.6/Documentation/magic-number.txt into Chinese
  ...

* 'usb-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6: (172 commits)
  USB: Add support for SuperSpeed isoc endpoints
  xhci: Clean up cycle bit math used during stalls.
  xhci: Fix cycle bit calculation during stall handling.
  xhci: Update internal dequeue pointers after stalls.
  USB: Disable auto-suspend for USB 3.0 hubs.
  USB: Remove bogus USB_PORT_STAT_SUPER_SPEED symbol.
  xhci: Return canceled URBs immediately when host is halted.
  xhci: Fixes for suspend/resume of shared HCDs.
  xhci: Fix re-init on power loss after resume.
  xhci: Make roothub functions deal with device removal.
  xhci: Limit roothub ports to 15 USB3 & 31 USB2 ports.
  xhci: Return a USB 3.0 hub descriptor for USB3 roothub.
  xhci: Register second xHCI roothub.
  xhci: Change xhci_find_slot_id_by_port() API.
  xhci: Refactor bus suspend state into a struct.
  xhci: Index with a port array instead of PORTSC addresses.
  USB: Set usb_hcd->state and flags for shared roothubs.
  usb: Make core allocate resources per PCI-device.
  usb: Store bus type in usb_hcd, not in driver flags.
  usb: Change usb_hcd->bandwidth_mutex to a pointer.
  ...

This is an ex-parrot.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

The last remaining instances of ->get_sb() can be converted ->mount()
now - nothing in them uses new vfsmount anymore.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

now we can do that - nobody cares about its value anymore.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

a) ->show_devname(m, mnt) - what to put into devname columns in mounts,
mountinfo and mountstats
b) ->show_path(m, mnt) - what to put into relative path column in mountinfo

Leaving those NULL gives old behaviour.  NFS switched to using those.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

It's always equal to dentry->d_sb
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

part 3: now we have everything to get nfs_path() just by dentry -
just follow to (disconnected) root and pick the rest of the thing
there.

Start killing propagation of struct vfsmount * on the paths that
used to bring it to nfs_path().
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>