[GIT PULL v2] Fix bugs in Slow-work, FS-Cache and CacheFiles

[David Howells <dhowells@redhat.com>]

Hi Linus,

Could you pull the attached patches before 2.6.32 please?  I've added three
one-liner patches to fix some silly bugs.

For the most part these patches are bug fixes for the slow-work, FS-Cache and
CacheFiles facilities, with a few patches to produce better debugging
information, and a couple of patches to slow work from Jens that all the rest
are built on top of.

These vastly improve the stability of FS-Cache under extremely high load -
especially when the system is running out of memory regularly.  I wrote a
better test case:

	http://people.redhat.com/~dhowells/slurp.c

which helped enormously in reproducing these bugs.  Testing has involved
running repeated invocations of slurp over five NFS4 mounted directory trees
totalling ~40GB in N file spread over 100,000 dirs on a machine with 1GB of
RAM and 4GB of disk cache space.  Note that slurp, being massively parallel,
will abandon a part of the tree if it hits any error (such as ENOMEM) - so not
all the data set will necessarily be used in any particular run.

The patches can also be downloaded as:

	http://people.redhat.com/~dhowells/fscache/patches/fscache-fixes.tar.bz2

The changes don't affect very much outside of FS-Cache and its dependents (NFS,
AFS and 9P), but the slow-work changes do affect CIFS and GFS2.

Thanks,
David
---
The following changes since commit 66b00a7c93ec782d118d2c03bd599cfd041e80a1:
  Linus Torvalds (1):
        Merge branch 'fixes' of git://git.kernel.org/.../davej/cpufreq

are available in the git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-2.6-fscache.git master

David Howells (28):
      SLOW_WORK: Wait for outstanding work items belonging to a module to clear
      SLOW_WORK: Allow the work items to be viewed through a /proc file
      SLOW_WORK: Allow the owner of a work item to determine if it is queued or not
      SLOW_WORK: Allow a requeueable work item to sleep till the thread is needed
      FS-Cache: Annotate slow-work runqueue proc lines for FS-Cache work items
      FS-Cache: Allow the current state of all objects to be dumped
      FS-Cache: Add counters for entry/exit to/from cache operation functions
      FS-Cache: Clear netfs pointers in cookie after detaching object, not before
      FS-Cache: Use radix tree preload correctly in tracking of pages to be stored
      FS-Cache: Permit cache retrieval ops to be interrupted in the initial wait phase
      FS-Cache: The object-available state can't rely on the cookie to be available
      FS-Cache: Fix lock misorder in fscache_write_op()
      FS-Cache: Don't delete pending pages from the page-store tracking tree
      FS-Cache: Handle read request vs lookup, creation or other cache failure
      FS-Cache: Handle pages pending storage that get evicted under OOM conditions
      FS-Cache: Add a retirement stat counter
      FS-Cache: Make sure FSCACHE_COOKIE_LOOKING_UP cleared on lookup failure
      FS-Cache: Start processing an object's operations on that object's death
      FS-Cache: Actually requeue an object when requested
      CacheFiles: Don't write a full page if there's only a partial page to cache
      CacheFiles: Handle truncate unlocking the page we're reading
      CacheFiles: Mark parent directory locks as I_MUTEX_PARENT to keep lockdep happy
      CacheFiles: Better showing of debugging information in active object problems
      CacheFiles: Catch an overly long wait for an old active object
      CacheFiles: Don't log lookup/create failing with ENOBUFS
      SLOW_WORK: Fix CIFS to pass THIS_MODULE to slow_work_register_user()
      SLOW_WORK: Fix GFS2 to #include <linux/module.h> before using THIS_MODULE
      FS-Cache: Provide nop fscache_stat_d() if CONFIG_FSCACHE_STATS=n

Jens Axboe (3):
      SLOW_WORK: Make slow_work_ops ->get_ref/->put_ref optional
      SLOW_WORK: Add support for cancellation of slow work
      SLOW_WORK: Add delayed_slow_work support

 Documentation/filesystems/caching/fscache.txt   |  110 +++++
 Documentation/filesystems/caching/netfs-api.txt |   21 +-
 Documentation/slow-work.txt                     |  160 +++++++-
 fs/9p/cache.c                                   |   14 +-
 fs/afs/file.c                                   |   15 +-
 fs/cachefiles/interface.c                       |   32 ++-
 fs/cachefiles/namei.c                           |  187 +++++++--
 fs/cachefiles/rdwr.c                            |  128 ++++++-
 fs/cifs/cifsfs.c                                |    2 +-
 fs/fscache/Kconfig                              |    7 +
 fs/fscache/Makefile                             |    1 +
 fs/fscache/cache.c                              |    5 +
 fs/fscache/cookie.c                             |   26 +-
 fs/fscache/internal.h                           |   56 +++
 fs/fscache/main.c                               |    6 +-
 fs/fscache/object-list.c                        |  432 ++++++++++++++++++++
 fs/fscache/object.c                             |  104 +++++-
 fs/fscache/operation.c                          |  120 +++++--
 fs/fscache/page.c                               |  273 ++++++++++---
 fs/fscache/proc.c                               |   13 +
 fs/fscache/stats.c                              |   94 ++++-
 fs/gfs2/main.c                                  |    4 +-
 fs/gfs2/recovery.c                              |    2 +
 fs/nfs/fscache.c                                |   10 +-
 include/linux/fscache-cache.h                   |   40 ++-
 include/linux/fscache.h                         |   27 ++
 include/linux/slow-work.h                       |   72 ++++-
 init/Kconfig                                    |   10 +
 kernel/Makefile                                 |    1 +
 kernel/slow-work-proc.c                         |  227 +++++++++++
 kernel/slow-work.c                              |  494 +++++++++++++++++++++--
 kernel/slow-work.h                              |   72 ++++
 lib/radix-tree.c                                |    5 +-
 33 files changed, 2505 insertions(+), 265 deletions(-)
 create mode 100644 fs/fscache/object-list.c
 create mode 100644 kernel/slow-work-proc.c
 create mode 100644 kernel/slow-work.h