Add "drop_inode" VFS interface to make FS operations cleaner
and race-free.  Remove old force_delete interface, and update
filesystems that used it to use the new infrastructure.

kill ->i_op->revalidate()

The lock.h header contained some hand-crafted lcoking routines from
the pre-SMP days.  In 2.5 only lock_super/unlock_super are left,
guarded by a number of completly unrelated (!) includes.

This patch moves lock_super/unlock_super to fs.h, which defined
struct super_block that is needed for those to operate it, removes
locks.h and updates all caller to not include it and add the missing,
previously nested includes where needed.

- Fixes a performance problem - callers of
  prepare_write/commit_write, etc are locking pages, which synchronises
  them behind writeback, which also locks these pages.  Significant
  slowdowns for some workloads.

- So pages are no longer locked while under writeout.  Introduce a
  new PG_writeback and associated infrastructure to support this design
  change.

- Pages which are under read I/O still use PageLocked.  Pages which
  are under write I/O have PageWriteback() true.

  I considered creating Page_IO instead of PageWriteback, and marking
  both readin and writeout pages as PageIO().  So pages are unlocked
  during both read and write.  There just doesn't seem a need to do
  this - nobody ever needs unblocking access to a page which is under
  read I/O.

- Pages under swapout (brw_page) are PageLocked, not PageWriteback.
  So their treatment is unchangeded.

  It's not obvious that pages which are under swapout actually need
  the more asynchronous behaviour of PageWriteback.

  I was setting the swapout pages PageWriteback and unlocking them
  prior to submitting the buffers in brw_page().  This led to deadlocks
  on the exit_mmap->zap_page_range->free_swap_and_cache path.  These
  functions call block_flushpage under spinlock.  If the page is
  unlocked but has locked buffers, block_flushpage->discard_buffer()
  sleeps.  Under spinlock.  So that will need fixing if for some reason
  we want swapout to use PageWriteback.

  Kernel has called block_flushpage() under spinlock for a long time.
   It is assuming that a locked page will never have locked buffers.
  This appears to be true, but it's ugly.

- Adds new function wait_on_page_writeback().  Renames wait_on_page()
  to wait_on_page_locked() to remind people that they need to call the
  appropriate one.

- Renames filemap_fdatasync() to filemap_fdatawrite().  It's more
  accurate - "sync" implies, if anything, writeout and wait.  (fsync,
  msync) Or writeout.  it's not clear.

- Subtly changes the filemap_fdatawrite() internals - this function
  used to do a lock_page() - it waited for any other user of the page
  to let go before submitting new I/O against a page.  It has been
  changed to simply skip over any pages which are currently under
  writeback.

  This is the right thing to do for memory-cleansing reasons.

  But it's the wrong thing to do for data consistency operations (eg,
  fsync()).  For those operations we must ensure that all data which
  was dirty *at the time of the system call* are tight on disk before
  the call returns.

  So all places which care about this have been converted to do:

	filemap_fdatawait(mapping);	/* Wait for current writeback */
	filemap_fdatawrite(mapping);	/* Write all dirty pages */
	filemap_fdatawait(mapping);	/* Wait for I/O to complete */

- Fixes a truncate_inode_pages problem - truncate currently will
  block when it hits a locked page, so it ends up getting into lockstep
  behind writeback and all of the file is pointlessly written back.

  One fix for this is for truncate to simply walk the page list in the
  opposite direction from writeback.

  I chose to use a separate cleansing pass.  It is more
  CPU-intensive, but it is surer and clearer.  This is because there is
  no reason why the per-address_space ->vm_writeback and
  ->writeback_mapping functions *have* to perform writeout in
  ->dirty_pages order.  They may choose to do something totally
  different.

  (set_page_dirty() is an a_op now, so address_spaces could almost
  privatise the whole dirty-page handling thing.  Except
  truncate_inode_pages and invalidate_inode_pages assume that the pages
  are on the address_space lists.  hmm.  So making truncate_inode_pages
  and invalidate_inode_pages a_ops would make some sense).

Moved i_sem down into notify_change() and out of the UMSDOS
function. Moved BKL down from notify_change into filesystems.

Seperates smb_sb_info from struct super_block.

The rest of nodev filesystems switched.

This patch adds LFS and moves some smb operations into per-protocol level
structs. It wants the nls patch to applied already.

Big bits first, I'll redo the smaller bits tomorrow after some sleep.
Same as last time, rediffed against pre5

smbfs switched to ->get_sb()

- Asit Mallick: mtrr update
- Patrick Mochel: split up kernel/device.c into drivers/base
- Mikael Pettersson/Al Viro: fix missing in-core inode initialization
in ext2 introduced by Al's inode trimming
- David Miller: sparc and network updates
- Frank Davis: firewire video mmap page remapping fix
- me: fix configure help scripts to fix breakage noticed by Dave Jones
- Greg KH: USB updates
- Kai Germaschewski: ISDN fixes, Config.help entries
- Douglas Gilbert: SCSI doc update
- Ingo Molnar: x86 taskswitch optimizations, scheduler updates
- Mikael Pettersson: make APIC work on old external setups
- Al Viro: more inode trimming

- Jeff Garzik: fix up loop and md for struct kdev_t typechecking
- Jeff Garzik: improved old-tulip network driver
- Arnaldo: more scsi driver bio updates
- Kai Germaschewski: ISDN updates
- various: kdev_t updates

  - Al Viro: superblock cleanups, partition handling fixes and cleanups
  - Ben Collins: firewire update
  - Jeff Garzik: network driver updates
  - Urban Widmark: smbfs updates
  - Kai Mäkisara: SCSI tape driver update
  - various: embarrassing lack of error checking in ELF loader
  - Neil Brown: md formatting cleanup.

  - me/Al Viro: fix bdget() oops with block device modules that don't
  clean up after they exit
  - Alan Cox: continued merging (drivers, license tags)
  - David Miller: sparc update, network fixes
  - Christoph Hellwig: work around broken drivers that add a gendisk more
  than once
  - Jakub Jelinek: handle more ELF loading special cases
  - Trond Myklebust: NFS client and lockd reclaimer cleanups/fixes
  - Greg KH: USB updates
  - Mikael Pettersson: sparate out local APIC / IO-APIC config options

  - Christoph Hellwig: clean up personality handling a bit
  - Robert Love: update sysctl/vm documentation
  - make the three-argument (that everybody hates) "min()" be "min_t()",
  and introduce a type-anal "min()" that complains about arguments of
  different types.

  - Chris Mason: ReiserFS pre-allocation locking bugfix
  - David Miller: fix bitops users (requires "long" alignment)
  - Andrey Savochkin: file locking failure case SMP lock fix
  - Urban Widmark: smbfs update (avoid unnecessary flushing, make NetApp
  work)
  - Andrew Grover: ACPI update
  - Jeff Garzik: network driver updates
  - Maciej Rozycki: IO-APIC level trigger problem workaround
  - Rusty Russell: ipt_unclean fix
  - Richard Gooch: devfs update

  - Al Viro: sanity-check user arguments, zero-terminated strings etc.
  - Urban Widmark: smbfs update (server/client cache coherency etc)
  - Rik van Riel, Marcelo Tosatti: VM updates
  - Cort Dougan: PPC updates
  - Neil Brown: raid1/5 failed drive fixups, NULL ptr checking, md error cleanup
  - Neil Brown: knfsd fix for 64-bit architectures, and filehandle resolveir
  - Ken Brownfield: workaround for menuconfig CPU selection glitch
  - David Miller: sparc64 MM setup fix, arpfilter forward port
  - Keith Owens: Remove obsolete IPv6 provider based addressing
  - Jari Ruusu: block_write error case cleanup fix
  - Jeff Garzik: netdriver update

  - Mike Phillips: olympic driver update
  - Alan Cox: continued resyncing (lots of small stuff, big NTFS merge from Anton)
  - Martin Dalecki: cleanup (remove unused and unnecessary get_hardblocksize)
  - Chris Mason: fix potential reiserfs journal overflow
  - Jeff Garzik: network driver updates
  - David Miller: sparc fixes, some network cleanups

  - Alan Cox: continued merging
  - Urban Widmark: smbfs fix (d_add on already hashed dentry - no-no).
  - Andrew Morton: 3c59x update
  - Jeff Garzik: network driver cleanups and fixes
  - Gérard Roudier: sym-ncr drivers update
  - Jens Axboe: more loop cleanups and fixes
  - David Miller: sparc update, some networking fixes

  - Chris Mason: reiserfs, another null bytes bug
  - Andrea Arkangeli: make SMP Athlon build
  - Alexander Zarochentcev: reiserfs directory fsync SMP locking fix
  - Jeff Garzik: PCI network driver updates
  - Alan Cox: continue merging
  - Ingo Molnar: fix RAID AUTORUN ioctl, scheduling improvements

  - sync up more with Alan
  - Urban Widmark: smbfs and HIGHMEM fix
  - Chris Mason: reiserfs tail unpacking fix ("null bytes in reiserfs files")
  - Adan Richter: new cpia usb ID
  - Hugh Dickins: misc small sysv ipc fixes
  - Andries Brouwer: remove overly restrictive sector size check for
  SCSI cd-roms

  - Jens: better ordering of requests when unable to merge
  - Neil Brown: make md work as a module again (we cannot autodetect
  in modules, not enough background information)
  - Neil Brown: raid5 SMP locking cleanups
  - Neil Brown: nfsd: handle Irix NFS clients named pipe behavior and
  dentry leak fix
  - maestro3 shutdown fix
  - fix dcache hash calculation that could cause bad hashes under certain
  circumstances (Dean Gaudet)
  - David Miller: networking and sparc updates
  - Jeff Garzik: include file cleanups
  - Andy Grover: ACPI update
  - Coda-fs error return fixes
  - rth: alpha Jensen update