All slabs which can be reclaimed via VM presure are marked as being
shrinkable, so the core slab code will keep count of their pages.

Except for the one in XFS.  It has strange wrapper stuff.

We have a problem at present in vm_enough_memory(): it uses smoke-n-mirrors
to try to work out how much memory can be reclaimed from dcache and icache.
it sometimes gets it quite wrong, especially if the slab has internal
fragmentation.  And it often does.

So here we take a new approach.  Rather than trying to work out how many
pages are reclaimable by counting up the number of inodes and dentries, we
change the slab allocator to keep count of how many pages are currently used
by slabs which can be shrunk by the VM.

The creator of the slab marks the slab as being reclaimable at
kmem_cache_create()-time.  Slab keeps a global counter of pages which are
currently in use by thus-tagged slabs.

Of course, we now slightly overestimate the amount of reclaimable memory,
because not _all_ of the icache, dcache, mbcache and quota caches are
reclaimable.

But I think it's better to be a bit permissive rather than bogusly failing
brk() calls as we do at present.

From: Neil Brown <neilb@cse.unsw.edu.au>

When an NFS request arrives, it contains a filehandle which needs to be
converted to a dentry.  Many filesystems use find_exported_dentry in
fs/exportfs/expfs.c.  A key part of this on filesystem where a 32bit inode
number uniquely locates a file is export_iget which calls iget(sb, inum).

iget will either:

   1/ find the inode in the inode cache and return it

 or

   2/ create a new inode and call ->read_inode to load it from the
      storage device.

export_iget then verifies the inode is really a good inode (->read_inode
didn't detect any problems) and the right inode (base on generation number
from the file handle).

For this to work reliably, it is important that whenever an inode is *not* in
the cache, the on-device version is up-to-date.  Otherwise, when read_inode
loads the inode it will get bad data.

For a file that has not been deleted, this condition always holds: a dirty
inode is always flushed to disc before the inode is unhashed.

However for a file that is being deleted this condition doesn't (didn't)
hold.  When iput -> iput_final -> generic_drop_inode -> generic_delete_inode
is called we would unhash the inode before calling into the filesytem through
->delete_inode.

So there is a small window between when generic_delete_inode unhashes the
inode, and when ->delete_inode writes something to disc, where a call to
->read_inode (for export_iget) might discover what it thinks is a valid
inode, but is really one that is in the process of being destroyed.

It is this window that I want to close by moving the unhashing to the end of
generic_delete_inode.

From: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>

There are a couple of places in the readdir code where it forgets to set
the returned error code to -EFAULT, leaving it at the default -EINVAL.

Fix that up, and rename getdents_callback64.count to "result", which makes
more sense.

From zwane

We shutdown the MAC part of the card and have interrupts disabled, interrupt
gets queued, we reenable interrupts after shutting down device, service the
interrupt, check status and get 0xff from powered down device.

No idea what he's talking about here, but apparently the irq return handling
isn't working out.  Just return IRQ_HANDLED all the time.

From: Oleg Drokin <green@namesys.com>

This is a forward port of 2.4's inode attributes support for reiserfs.
Original implementation for 2.4 was performed by Nikita Danilov.

In order to enable this support, one must use "attrs" mount options, eg:

	mount /dev/hda1 /mount/pont -t reiserfs -o attrs

Also either the filesystem must have been created with a recent mkreiserfs
or must have been modified by a recent version of reiserfsck with its
"--clean-attributes" option.

If that is not done, attributes support will not be enabled and a kernel
message will be printed.  This is necessary because old kernels left random
garbage in the place where these attributes now live.

These attributes are totally compatible with ext2's ones.  You can
manipulate them with chattr/lsattr etc.

Additionally the chattr 'd' option may be used to disable tail packing on a
specific file or a directory tree.  (The 'd' option normally means "don't
dump".  reiserfs has overloaded it).

From: Zwane Mwaikambo <zwane@linuxpower.ca>

kapmd does a conditional check in order to decide whether to set the task's
cpu affinity mask.  This can change during runtime, therefore we
unconditionally set it.  There is an early exit in set_cpus_allowed if the
current processor is in the allowed mask anyway.

__unhash_process acquires the dcache_lock while holding the
tasklist_lock for writing. This can deadlock. Additionally,
fs/proc/base.c incorrectly assumed that p->pid would be set to 0 during
release_task.

The patch fixes that by adding a new spinlock to the task structure and
fixing all references to (!p->pid).

The alternative to the new spinlock would be to hold dcache_lock around
__unhash_process.

- fs/proc/base.c assumed that p->pid is reset to 0 during exit.  This is
  not the case anymore.  I now look at the count of the pid structure for
  PIDTYPE_PID.

- de_thread now tested - as broken as it was before: open handles to
  /proc/<pid> are either stale or invalid after an exec of a nptl process,
  if the exec was call from a secondary thread.

- a few lock_kernels removed - that part of /proc doesn't need it.

- additional instances of 'if(current->pid)' replaced with pid_alive.

From: William Lee Irwin III <wli@holomorphy.com>

mpc_apicid is a u8, and MAX_APICS can be 256.

fs/compat.c: In function `compat_sys_ioctl':
fs/compat.c:324: warning: implicit declaration of function `siocdevprivate_ioctl'

Don't assume the size of dev_t: on ppc64 it is unsignedlong and this
generates a printk warning.

arch/ppc64/kernel/htab.c:105: warning: implicit declaration of function `pSeries_lpar_hpte_insert'
arch/ppc64/kernel/htab.c:109: warning: implicit declaration of function `pSeries_hpte_insert'

Fix a printk warning

two printk warnings

warning: assignment makes pointer from integer without a cast

It needs sched.h for `current'.

From: David Gibson <david@gibson.dropbear.id.au>

This removes a bunch of unused variables in prom_init(), squashing the
associated warnings.

From: David Gibson <david@gibson.dropbear.id.au>

xics.c uses ppc64_boot_msg() without prototype, this fixes it by inclding
<asm/machdep.h>.

do_signal32() is used before it is defined, this prototype squashes the
warning.

From: David Gibson <david@gibson.dropbear.id.au>

Squash implicit declaration warning in ppc64 align.c

From: David Gibson <david@gibson.dropbear.id.au>

addnote in arch/ppc64/boot (a userspace tool, not kernel code) uses exit()
without including stdlib.h.

PPC64 irq return fix

Fix some warnings in the ppc64 build.

Also declare a couple of AIO functions in aio.h rather than aio.c They are
needed for 32-bit emulation support.

From: Anton Blanchard <anton@samba.org>

PPC64 32/64-bit emulation for AIO.

Very early initialization (core_initcall) needs to have the cdev
initialization done.  So make it part of the pre-initcall sequence, the
same way the bdev caches were done.

This addresses a futex related SMP scalability problem of
glibc. A number of regressions have been reported to the NTPL mailing list
when going to many CPUs, for applications that use condition variables and
the pthread_cond_broadcast() API call. Using this functionality, testcode
shows a slowdown from 0.12 seconds runtime to over 237 seconds (!)
runtime, on 4-CPU systems.

pthread condition variables use two futex-backed mutex-alike locks: an
internal one for the glibc CV state itself, and a user-supplied mutex
which the API guarantees to take in certain codepaths. (Unfortunately the
user-supplied mutex cannot be used to protect the CV state, so we've got
to deal with two locks.)

The cause of the slowdown is a 'swarm effect': if lots of threads are
blocked on a condition variable, and pthread_cond_broadcast() is done,
then glibc first does a FUTEX_WAKE on the cv-internal mutex, then down a
mutex_down() on the user-supplied mutex. Ie. a swarm of threads is created
which all race to serialize on the user-supplied mutex. The more threads
are used, the more likely it becomes that the scheduler will balance them
over to other CPUs - where they just schedule, try to lock the mutex, and
go to sleep. This 'swarm effect' is purely technical, a side-effect of
glibc's use of futexes, and the imperfect coupling of the two locks.

the solution to this problem is to not wake up the swarm of threads, but
'requeue' them from the CV-internal mutex to the user-supplied mutex. The
attached patch adds the FUTEX_REQUEUE feature FUTEX_REQUEUE requeues N
threads from futex address A to futex address B.

This way glibc can wake up a single thread (which will take the
user-mutex), and can requeue the rest, with a single system-call.

Ulrich Drepper has implemented FUTEX_REQUEUE support in glibc, and a
number of people have tested it over the past couple of weeks. Here are
the measurements done by Saurabh Desai:

System: 4xPIII 700MHz

 ./cond-perf -r 100 -n 200:        1p       2p         4p
 Default NPTL:                 0.120s   0.211s   237.407s
 requeue NPTL:                 0.124s   0.156s     0.040s

 ./cond-perf -r 1000 -n 100:
 Default NPTL:                 0.276s   0.412s     0.530s
 requeue NPTL:                 0.349s   0.503s     0.550s

 ./pp -v -n 128 -i 1000 -S 32768:
 Default NPTL: 128 games in    1.111s   1.270s    16.894s
 requeue NPTL: 128 games in    1.111s   1.959s     2.426s

 ./pp -v -n 1024 -i 10 -S 32768:
 Default NPTL: 1024 games in   0.181s   0.394s     incompleted 2m+
 requeue NPTL: 1024 games in   0.166s   0.254s     0.341s

the speedup with increasing number of threads is quite significant, in the
128 threads, case it's more than 8 times. In the cond-perf test, on 4 CPUs
it's almost infinitely faster than the 'swarm of threads' catastrophy
triggered by the old code.

new fields in struct inode - i_cdev and i_cindex.  When we do open() on
a character device we cache result of cdev lookup in inode and put the
inode on a cyclic list anchored in cdev.  If we already have that done,
we don't bother with any lookups.  When inode disappears it's removed
from the list.  When cdev gets unregistered we remove all cached
references to it (and remove such inodes from the list).  cdev is held
until final fput() now.

New object: struct cdev.  It contains a kobject, a pointer to
file_operations and a pointer to owner module.  These guys have a search
structure of the same sort as gendisks and chrdev_open() picks
file_operations from them.

Intended use: embed such animal in driver-owned structure (e.g.
tty_driver) and register it as associated with given range of device
numbers.  Generic code will do lookup for such object and use it for the
rest.

The behaviour of register_chrdev() is _not_ changed - it allocates
struct cdev and registers it; any old driver will work as if nothing had
changed.

On that stage we only use it during chrdev_open() to find
file_operations.  Later it will be cached in inode->i_cdev (and index in
range - in inode->i_cindex) so that ->open() could get whatever objects
it wants directly without any special-cased lookups, etc.

code responsible for gendisk lookups taken out in drivers/base and
generalized - now it allows to have a range-based mapping from numbers
to kobjects for given struct subsystem.

register_chrdev_region() sanitized, code in tty_io.c that dealt with it
cleaned up.

preparation to cdev-cidr - the lookup mechanism for gendisks is switched
to dealing with disk->kobj instead of disk.

pt.c fed through Lindent

Remove cpp abuses - same as had been done for pd/pf/pcd.

Remove the rest of cpp abuse in pg.c

pg.c fed through Lindent

This removes cpp abuses - same as had been done for pd/pf/pcd.

This restores the special-case behaviour of open() on the minor 0;
cpqarray allows to open that guy for ioctls even if nothing is
configured.  That got broken when gendisk patches went in.  Patch
restores the old behaviour by keeping gendisk for the first disk on
controller always registered; instead of unregistering it we set size to
0.

This fixes the TIOCCONS race; it's the same as the 2.4 patch except for
a fix for a brown-paperbag bug in it.

Forgot to remove include/asm-ppc/linux_logo.h when integrating the new logo
code.