It's possible for a device in the drhd->devices[] array to be NULL if
it wasn't found at boot time, which means we have to check for that
case.
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

We were comparing {bus,devfn} and assuming that a match meant it was the
same device. It doesn't -- the same {bus,devfn} can exist in
multiple PCI domains. Include domain number in device identification
(and call it 'segment' in most places, because there's already a lot of
references to 'domain' which means something else, and this code is
infected with ACPI thinking already).
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

When the DMAR table identifies that a PCI-PCI bridge belongs to a given
IOMMU, that means that the bridge and all devices behind it should be
associated with the IOMMU. Not just the bridge itself.

This fixes the device_to_iommu() function accordingly.

(It's broken if you have the same PCI bus numbers in multiple domains,
but this function was always broken in that way; I'll be dealing with
that later).
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

interrupt remapping must be enabled before enabling x2apic, but
interrupt remapping doesn't depend on x2apic, it can be used
separately. Enable interrupt remapping in init_dmars even x2apic
is not supported.

[dwmw2: Update Kconfig accordingly, fix build with INTR_REMAP && !X2APIC]
Signed-off-by: Weidong Han <weidong.han@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

If queue invalidation is disabled after it's already initialized,
dmar_enable_qi won't re-enable it due to iommu->qi is allocated.
It may result in system hang when use queue invalidation. Add this
check to avoid this case.
Signed-off-by: Weidong Han <weidong.han@intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

When extended interrupt mode (x2apic mode) is not supported in a
system, it must set compatibility format interrupt to bypass
interrupt remapping, otherwise compatibility format interrupts
will be blocked.

This will be used when interrupt remapping is enabled while x2apic
is not supported.
Signed-off-by: Weidong Han <weidong.han@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

This patch enables suspend/resume for interrupt remapping. During suspend,
interrupt remapping is disabled. When resume, interrupt remapping is enabled
again.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

This patch supports queued invalidation suspend/resume.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

This patch implements the suspend and resume feature for Intel IOMMU
DMAR. It hooks to kernel suspend and resume interface. When suspend happens, it
saves necessary hardware registers. When resume happens, it restores the
registers and restarts IOMMU by enabling translation, setting up root entry, and
re-enabling queued invalidation.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>

* 'ext3-latency-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext3: Add replace-on-rename hueristics for data=writeback mode
  ext3: Add replace-on-truncate hueristics for data=writeback mode
  ext3: Use WRITE_SYNC for commits which are caused by fsync()
  block_write_full_page: Use synchronous writes for WBC_SYNC_ALL writebacks

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/lrg/voltage-2.6: (32 commits)
  regulator: twl4030 VAUX3 supports 3.0V
  regulator: Support disabling of unused regulators by machines
  regulator: Don't increment use_count for boot_on regulators
  twl4030-regulator: expose VPLL2
  regulator: refcount fixes
  regulator: Don't warn if we failed to get a regulator
  regulator: Allow boot_on regulators to be disabled by clients
  regulator: Implement list_voltage for WM835x LDOs and DCDCs
  twl4030-regulator: list more VAUX4 voltages
  regulator: Don't warn on omitted voltage constraints
  regulator: Implement list_voltage() for WM8400 DCDCs and LDOs
  MMC: regulator utilities
  regulator: twl4030 voltage enumeration (v2)
  regulator: twl4030 regulators
  regulator: get_status() grows kerneldoc
  regulator: enumerate voltages (v2)
  regulator: Fix get_mode() for WM835x DCDCs
  regulator: Allow regulators to set the initial operating mode
  regulator: Suggest use of datasheet supply or pin names for consumers
  regulator: email - update email address and regulator webpage.
  ...

* git://git.infradead.org/iommu-2.6:
  intel-iommu: Fix address wrap on 32-bit kernel.
  intel-iommu: Enable DMAR on 32-bit kernel.
  intel-iommu: fix PCI device detach from virtual machine
  intel-iommu: VT-d page table to support snooping control bit
  iommu: Add domain_has_cap iommu_ops
  intel-iommu: Snooping control support

Fixed trivial conflicts in arch/x86/Kconfig and drivers/pci/intel-iommu.c

* git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-2.6-fscache: (41 commits)
  NFS: Add mount options to enable local caching on NFS
  NFS: Display local caching state
  NFS: Store pages from an NFS inode into a local cache
  NFS: Read pages from FS-Cache into an NFS inode
  NFS: nfs_readpage_async() needs to be accessible as a fallback for local caching
  NFS: Add read context retention for FS-Cache to call back with
  NFS: FS-Cache page management
  NFS: Add some new I/O counters for FS-Cache doing things for NFS
  NFS: Invalidate FsCache page flags when cache removed
  NFS: Use local disk inode cache
  NFS: Define and create inode-level cache objects
  NFS: Define and create superblock-level objects
  NFS: Define and create server-level objects
  NFS: Register NFS for caching and retrieve the top-level index
  NFS: Permit local filesystem caching to be enabled for NFS
  NFS: Add FS-Cache option bit and debug bit
  NFS: Add comment banners to some NFS functions
  FS-Cache: Make kAFS use FS-Cache
  CacheFiles: A cache that backs onto a mounted filesystem
  CacheFiles: Export things for CacheFiles
  ...

* git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-2.6-dm: (36 commits)
  dm: set queue ordered mode
  dm: move wait queue declaration
  dm: merge pushback and deferred bio lists
  dm: allow uninterruptible wait for pending io
  dm: merge __flush_deferred_io into caller
  dm: move bio_io_error into __split_and_process_bio
  dm: rename __split_bio
  dm: remove unnecessary struct dm_wq_req
  dm: remove unnecessary work queue context field
  dm: remove unnecessary work queue type field
  dm: bio list add bio_list_add_head
  dm snapshot: persistent fix dtr cleanup
  dm snapshot: move status to exception store
  dm snapshot: move ctr parsing to exception store
  dm snapshot: use DMEMIT macro for status
  dm snapshot: remove dm_snap header
  dm snapshot: remove dm_snap header use
  dm exception store: move cow pointer
  dm exception store: move chunk_fields
  dm exception store: move dm_target pointer
  ...

* 'for-linus' of git://git.open-osd.org/linux-open-osd:
  fs: Add exofs to Kernel build
  exofs: Documentation
  exofs: export_operations
  exofs: super_operations and file_system_type
  exofs: dir_inode and directory operations
  exofs: address_space_operations
  exofs: symlink_inode and fast_symlink_inode operations
  exofs: file and file_inode operations
  exofs: Kbuild, Headers and osd utils

* 'for-linus' of git://oss.sgi.com/xfs/xfs: (61 commits)
  Revert "xfs: increase the maximum number of supported ACL entries"
  xfs: cleanup uuid handling
  xfs: remove m_attroffset
  xfs: fix various typos
  xfs: pagecache usage optimization
  xfs: remove m_litino
  xfs: kill ino64 mount option
  xfs: kill mutex_t typedef
  xfs: increase the maximum number of supported ACL entries
  xfs: factor out code to find the longest free extent in the AG
  xfs: kill VN_BAD
  xfs: kill vn_atime_* helpers.
  xfs: cleanup xlog_bread
  xfs: cleanup xlog_recover_do_trans
  xfs: remove another leftover of the old inode log item format
  xfs: cleanup log unmount handling
  Fix xfs debug build breakage by pushing xfs_error.h after
  xfs: include header files for prototypes
  xfs: make symbols static
  xfs: move declaration to header file
  ...

* git://git.kernel.org/pub/scm/linux/kernel/git/kyle/parisc-2.6: (23 commits)
  parisc: move dereference_function_descriptor to process.c
  parisc: Move kernel Elf_Fdesc define to <asm/elf.h>
  parisc: fix build when ARCH_HAS_KMAP
  parisc: fix "make tar-pkg"
  parisc: drivers: fix warnings
  parisc: select BUG always
  parisc: asm/pdc.h should include asm/page.h
  parisc: led: remove proc_dir_entry::owner
  parisc: fix macro expansion in atomic.h
  parisc: iosapic: fix build breakage
  parisc: oops_enter()/oops_exit() in die()
  parisc: document light weight syscall ABI
  parisc: blink all or loadavg LEDs on oops
  parisc: add ftrace (function and graph tracer) functionality
  parisc: simplify sys_clone()
  parisc: add LATENCYTOP_SUPPORT and CONFIG_STACKTRACE_SUPPORT
  parisc: allow to build with 16k default kernel page size
  parisc: expose 32/64-bit capabilities in cpuinfo
  parisc: use constants instead of numbers in assembly
  parisc: fix usage of 32bit PTE page table entries on 32bit kernels
  ...

* git://git.kernel.org/pub/scm/linux/kernel/git/kyle/rtc-parisc:
  powerpc/ps3: Add rtc-ps3
  powerpc: Hook up rtc-generic, and kill rtc-ppc
  m68k: Hook up rtc-generic
  parisc: rtc: Rename rtc-parisc to rtc-generic
  parisc: rtc: Add missing module alias
  parisc: rtc: platform_driver_probe() fixups
  parisc: rtc: get_rtc_time() returns unsigned int

* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-udf-2.6:
  udf: Don't write integrity descriptor too often
  udf: Try anchor in block 256 first
  udf: Some type fixes and cleanups
  udf: use hardware sector size
  udf: fix novrs mount option
  udf: Fix oops when invalid character in filename occurs
  udf: return f_fsid for statfs(2)
  udf: Add checks to not underflow sector_t
  udf: fix default mode and dmode options handling
  udf: fix sparse warnings:
  udf: unsigned last[i] cannot be less than 0
  udf: implement mode and dmode mounting options
  udf: reduce stack usage of udf_get_filename
  udf: reduce stack usage of udf_load_pvoldesc
  Fix the udf code not to pass structs on stack where possible.
  Remove struct typedefs from fs/udf/ecma_167.h et al.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/rcu-doc-2.6:
  Doc: Fix spelling in RCU/rculist_nulls.txt.
  Doc: Fix wrong API example usage of call_rcu().
  Doc: Fix missing whitespaces in RCU documentation.

Commit 7ca43e75 ("mm: use debug_kmap_atomic")
introduced some debug_kmap_atomic() in wrong places.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit f4112de6 ("mm: introduce
debug_kmap_atomic") broke PPC builds with CONFIG_HIGHMEM=y:

   CC      init/main.o
  In file included from include/linux/highmem.h:25,
                   from include/linux/pagemap.h:11,
                   from include/linux/mempolicy.h:63,
                   from init/main.c:53:
  arch/powerpc/include/asm/highmem.h: In function 'kmap_atomic_prot':
  arch/powerpc/include/asm/highmem.h:98: error: implicit declaration of function 'debug_kmap_atomic'
  In file included from include/linux/pagemap.h:11,
                   from include/linux/mempolicy.h:63,
                   from init/main.c:53:
  include/linux/highmem.h: At top level:
  include/linux/highmem.h:196: warning: conflicting types for 'debug_kmap_atomic'
  include/linux/highmem.h:196: error: static declaration of 'debug_kmap_atomic' follows non-static declaration
  include/asm/highmem.h:98: error: previous implicit declaration of 'debug_kmap_atomic' was here
  make[1]: *** [init/main.o] Error 1
  make: *** [init] Error 2
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Acked-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

* git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
  crypto: ixp4xx - Fix handling of chained sg buffers
  crypto: shash - Fix unaligned calculation with short length
  hwrng: timeriomem - Use phys address rather than virt

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu: (41 commits)
  m68knommu: improve compile arch switch settings
  m68knommu: fix 5407 ColdFire UART vector setup
  m68knommu: fix 5307 ColdFire UART vector setup
  m68knommu: fix 5249 ColdFire UART vector setup
  m68knommu: fix 5249 ColdFire UART setup
  m68knommu: fix end of uart table marker
  m68knommu: switch to using generic_handle_irq()
  m68k: merge the mmu and non-mmu versions of tlbflush.h
  m68knommu: introduce basic clk infrastructure
  m68k: merge the mmu and non-mmu versions of module.h
  m68knommu: add missing interrupt line definition for UART 2
  m68k: merge the mmu and non-mmu versions of mmu_context.h
  m68k: merge the mmu and non-mmu versions of current.h
  m68k: merge the mmu and non-mmu versions of div64.h
  m68k: merge the mmu and non-mmu versions of bugs.h
  m68k: merge the mmu and non-mmu versions of bug.h
  m68k: use the mmu version of cache.h for m68knommu as well
  m68k: use the mmu version of bootinfo.h for m68knommu as well
  m68k: merge the mmu and non-mmu versions of fb.h
  m68k: merge the mmu and non-mmu versions of segment.h
  ...

* 'for-linus' of git://neil.brown.name/md: (53 commits)
  md/raid5 revise rules for when to update metadata during reshape
  md/raid5: minor code cleanups in make_request.
  md: remove CONFIG_MD_RAID_RESHAPE config option.
  md/raid5: be more careful about write ordering when reshaping.
  md: don't display meaningless values in sysfs files resync_start and sync_speed
  md/raid5: allow layout and chunksize to be changed on active array.
  md/raid5: reshape using largest of old and new chunk size
  md/raid5: prepare for allowing reshape to change layout
  md/raid5: prepare for allowing reshape to change chunksize.
  md/raid5: clearly differentiate 'before' and 'after' stripes during reshape.
  Documentation/md.txt update
  md: allow number of drives in raid5 to be reduced
  md/raid5: change reshape-progress measurement to cope with reshaping backwards.
  md: add explicit method to signal the end of a reshape.
  md/raid5: enhance raid5_size to work correctly with negative delta_disks
  md/raid5: drop qd_idx from r6_state
  md/raid6: move raid6 data processing to raid6_pq.ko
  md: raid5 run(): Fix max_degraded for raid level 4.
  md: 'array_size' sysfs attribute
  md: centralize ->array_sectors modifications
  ...

* master.kernel.org:/home/rmk/linux-2.6-arm:
  [ARM] fix build-breaking 7a192ec3 commit
  ARM: Add SMSC911X support to Overo platform (V2)
  arm: update omap_ldp defconfig to use smsc911x
  arm: update realview defconfigs to use smsc911x
  arm: update pcm037 defconfig to use smsc911x
  arm: convert omap ldp platform to use smsc911x
  arm: convert realview platform to use smsc911x
  arm: convert pcm037 platform to use smsc911x
  [ARM] 5444/1: ARM: Realview: Fix event-device multiplicators in localtimer.c
  [ARM] 5442/1: pxa/cm-x255: fix reverse RDY gpios in PCMCIA driver
  [ARM] 5441/1: Use pr_err on error paths in at91 pm
  [ARM] 5440/1: Fix VFP state corruption due to preemption during VFP exceptions
  [ARM] 5439/1: Do not clear bit 10 of DFSR during abort handling on ARMv6
  [ARM] 5437/1: Add documentation for "nohlt" kernel parameter
  [ARM] 5436/1: ARM: OMAP: Fix compile for rx51
  [ARM] arch_reset() now takes a second parameter
  [ARM] Kirkwood: small L2 code cleanup
  [ARM] Kirkwood: invalidate L2 cache before enabling it

* git://git.kernel.org/pub/scm/linux/kernel/git/bart/linux-hdreg-h-cleanup:
  remove <linux/ata.h> include from <linux/hdreg.h>
  include/linux/hdreg.h: remove unused defines
  isd200: use ATA_* defines instead of *_STAT and *_ERR ones
  include/linux/hdreg.h: cover WIN_* and friends with #ifndef/#endif __KERNEL__
  aoe: WIN_* -> ATA_CMD_*
  isd200: WIN_* -> ATA_CMD_*
  include/linux/hdreg.h: cover struct hd_driveid with #ifndef/#endif __KERNEL__
  xsysace: make it 'struct hd_driveid'-free
  ubd_kern: make it 'struct hd_driveid'-free
  isd200: make it 'struct hd_driveid'-free

Add NFS mount options to allow the local caching support to be enabled.

The attached patch makes it possible for the NFS filesystem to be told to make
use of the network filesystem local caching service (FS-Cache).

To be able to use this, a recent nfsutils package is required.

There are three variant NFS mount options that can be added to a mount command
to control caching for a mount.  Only the last one specified takes effect:

 (*) Adding "fsc" will request caching.

 (*) Adding "fsc=<string>" will request caching and also specify a uniquifier.

 (*) Adding "nofsc" will disable caching.

For example:

	mount warthog:/ /a -o fsc

The cache of a particular superblock (NFS FSID) will be shared between all
mounts of that volume, provided they have the same connection parameters and
are not marked 'nosharecache'.

Where it is otherwise impossible to distinguish superblocks because all the
parameters are identical, but the 'nosharecache' option is supplied, a
uniquifying string must be supplied, else only the first mount will be
permitted to use the cache.

If there's a key collision, then the second mount will disable caching and give
a warning into the kernel log.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>

Display the local caching state in /proc/fs/nfsfs/volumes.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>

Store pages from an NFS inode into the cache data storage object associated
with that inode.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>

Read pages from an FS-Cache data storage object representing an inode into an
NFS inode.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>

nfs_readpage_async() needs to be non-static so that it can be used as a
fallback for the local on-disk caching should an EIO crop up when reading the
cache.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>

Add read context retention so that FS-Cache can call back into NFS when a read
operation on the cache fails EIO rather than reading data.  This permits NFS to
then fetch the data from the server instead using the appropriate security
context.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>

FS-Cache page management for NFS.  This includes hooking the releasing and
invalidation of pages marked with PG_fscache (aka PG_private_2) and waiting for
completion of the write-to-cache flag (PG_fscache_write aka PG_owner_priv_2).
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>

Add some new NFS I/O counters for FS-Cache doing things for NFS.  A new line is
emitted into /proc/pid/mountstats if caching is enabled that looks like:

	fsc: <rok> <rfl> <wok> <wfl> <unc>

Where <rok> is the number of pages read successfully from the cache, <rfl> is
the number of failed page reads against the cache, <wok> is the number of
successful page writes to the cache, <wfl> is the number of failed page writes
to the cache, and <unc> is the number of NFS pages that have been disconnected
from the cache.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>

Invalidate the FsCache page flags on the pages belonging to an inode when the
cache backing that NFS inode is removed.

This allows a live cache to be withdrawn.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>

Bind data storage objects in the local cache to NFS inodes.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>

Define and create inode-level cache data storage objects (as managed by
nfs_inode structs).

Each inode-level object is created in a superblock-level index object and is
itself a data storage object into which pages from the inode are stored.

The inode object key is the NFS file handle for the inode.

The inode object is given coherency data to carry in the auxiliary data
permitted by the cache.  This is a sequence made up of:

 (1) i_mtime from the NFS inode.

 (2) i_ctime from the NFS inode.

 (3) i_size from the NFS inode.

 (4) change_attr from the NFSv4 attribute data.

As the cache is a persistent cache, the auxiliary data is checked when a new
NFS in-memory inode is set up that matches an already existing data storage
object in the cache.  If the coherency data is the same, the on-disk object is
retained and used; if not, it is scrapped and a new one created.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>

Define and create superblock-level cache index objects (as managed by
nfs_server structs).

Each superblock object is created in a server level index object and is itself
an index into which inode-level objects are inserted.

Ideally there would be one superblock-level object per server, and the former
would be folded into the latter; however, since the "nosharecache" option
exists this isn't possible.

The superblock object key is a sequence consisting of:

 (1) Certain superblock s_flags.

 (2) Various connection parameters that serve to distinguish superblocks for
     sget().

 (3) The volume FSID.

 (4) The security flavour.

 (5) The uniquifier length.

 (6) The uniquifier text.  This is normally an empty string, unless the fsc=xyz
     mount option was used to explicitly specify a uniquifier.

The key blob is of variable length, depending on the length of (6).

The superblock object is given no coherency data to carry in the auxiliary data
permitted by the cache.  It is assumed that the superblock is always coherent.

This patch also adds uniquification handling such that two otherwise identical
superblocks, at least one of which is marked "nosharecache", won't end up
trying to share the on-disk cache.  It will be possible to manually provide a
uniquifier through a mount option with a later patch to avoid the error
otherwise produced.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>