[GIT PULL] FS-Cache and CacheFiles with AFS and NFS support

From: David Howells
Date: Fri Apr 03 2009 - 12:16:39 EST

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The following changes since commit 8fe74cf053de7ad2124a894996f84fa890a81093:
Linus Torvalds (1):
Merge branch 'for-linus' of git://git.kernel.org/.../viro/vfs-2.6

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 (41):
Create a dynamically sized pool of threads for doing very slow work items
Make slow-work thread pool actually dynamic
Make the slow work pool configurable
Document the slow work thread pool
FS-Cache: Release page->private after failed readahead
FS-Cache: Recruit a page flags for cache management
FS-Cache: Add the FS-Cache netfs API and documentation
FS-Cache: Add the FS-Cache cache backend API and documentation
FS-Cache: Add main configuration option, module entry points and debugging
FS-Cache: Add use of /proc and presentation of statistics
FS-Cache: Root index definition
FS-Cache: Add cache tag handling
FS-Cache: Add cache management
FS-Cache: Provide a slab for cookie allocation
FS-Cache: Add netfs registration
FS-Cache: Bit waiting helpers
FS-Cache: Object management state machine
FS-Cache: Implement the cookie management part of the netfs API
FS-Cache: Add and document asynchronous operation handling
FS-Cache: Implement data I/O part of netfs API
CacheFiles: Permit the page lock state to be monitored
CacheFiles: Export things for CacheFiles
CacheFiles: A cache that backs onto a mounted filesystem
FS-Cache: Make kAFS use FS-Cache
NFS: Add comment banners to some NFS functions
NFS: Add FS-Cache option bit and debug bit
NFS: Permit local filesystem caching to be enabled for NFS
NFS: Register NFS for caching and retrieve the top-level index
NFS: Define and create server-level objects
NFS: Define and create superblock-level objects
NFS: Define and create inode-level cache objects
NFS: Use local disk inode cache
NFS: Invalidate FsCache page flags when cache removed
NFS: Add some new I/O counters for FS-Cache doing things for NFS
NFS: FS-Cache page management
NFS: Add read context retention for FS-Cache to call back with
NFS: nfs_readpage_async() needs to be accessible as a fallback for local caching
NFS: Read pages from FS-Cache into an NFS inode
NFS: Store pages from an NFS inode into a local cache
NFS: Display local caching state
NFS: Add mount options to enable local caching on NFS

Documentation/filesystems/caching/backend-api.txt | 658 +++++++++++++++
Documentation/filesystems/caching/cachefiles.txt | 501 ++++++++++++
Documentation/filesystems/caching/fscache.txt | 333 ++++++++
Documentation/filesystems/caching/netfs-api.txt | 778 ++++++++++++++++++
Documentation/filesystems/caching/object.txt | 313 ++++++++
Documentation/filesystems/caching/operations.txt | 213 +++++
Documentation/slow-work.txt | 174 ++++
fs/Kconfig | 7 +
fs/Makefile | 2 +
fs/afs/Kconfig | 8 +
fs/afs/Makefile | 3 +
fs/afs/cache.c | 503 ++++++++-----
fs/afs/cache.h | 15 +-
fs/afs/cell.c | 16 +-
fs/afs/file.c | 220 ++++--
fs/afs/inode.c | 31 +-
fs/afs/internal.h | 53 +-
fs/afs/main.c | 27 +-
fs/afs/mntpt.c | 4 +-
fs/afs/vlocation.c | 25 +-
fs/afs/volume.c | 14 +-
fs/afs/write.c | 21 +
fs/cachefiles/Kconfig | 39 +
fs/cachefiles/Makefile | 18 +
fs/cachefiles/bind.c | 286 +++++++
fs/cachefiles/daemon.c | 755 ++++++++++++++++++
fs/cachefiles/interface.c | 449 +++++++++++
fs/cachefiles/internal.h | 360 +++++++++
fs/cachefiles/key.c | 159 ++++
fs/cachefiles/main.c | 106 +++
fs/cachefiles/namei.c | 771 ++++++++++++++++++
fs/cachefiles/proc.c | 134 ++++
fs/cachefiles/rdwr.c | 879 +++++++++++++++++++++
fs/cachefiles/security.c | 116 +++
fs/cachefiles/xattr.c | 291 +++++++
fs/fscache/Kconfig | 56 ++
fs/fscache/Makefile | 19 +
fs/fscache/cache.c | 415 ++++++++++
fs/fscache/cookie.c | 500 ++++++++++++
fs/fscache/fsdef.c | 144 ++++
fs/fscache/histogram.c | 109 +++
fs/fscache/internal.h | 380 +++++++++
fs/fscache/main.c | 124 +++
fs/fscache/netfs.c | 103 +++
fs/fscache/object.c | 810 +++++++++++++++++++
fs/fscache/operation.c | 459 +++++++++++
fs/fscache/page.c | 816 +++++++++++++++++++
fs/fscache/proc.c | 68 ++
fs/fscache/stats.c | 212 +++++
fs/nfs/Kconfig | 8 +
fs/nfs/Makefile | 1 +
fs/nfs/client.c | 14 +-
fs/nfs/file.c | 38 +-
fs/nfs/fscache-index.c | 337 ++++++++
fs/nfs/fscache.c | 523 ++++++++++++
fs/nfs/fscache.h | 220 +++++
fs/nfs/inode.c | 14 +
fs/nfs/internal.h | 4 +
fs/nfs/iostat.h | 18 +
fs/nfs/read.c | 27 +-
fs/nfs/super.c | 45 +-
fs/splice.c | 3 +-
fs/super.c | 1 +
include/linux/fscache-cache.h | 505 ++++++++++++
include/linux/fscache.h | 618 +++++++++++++++
include/linux/nfs_fs.h | 13 +
include/linux/nfs_fs_sb.h | 11 +
include/linux/nfs_iostat.h | 12 +
include/linux/page-flags.h | 40 +-
include/linux/pagemap.h | 5 +
include/linux/slow-work.h | 95 +++
init/Kconfig | 12 +
kernel/Makefile | 1 +
kernel/slow-work.c | 640 +++++++++++++++
kernel/sysctl.c | 9 +
mm/filemap.c | 21 +
mm/migrate.c | 10 +-
mm/readahead.c | 40 +-
mm/swap.c | 4 +-
mm/truncate.c | 10 +-
mm/vmscan.c | 6 +-
security/security.c | 2 +
82 files changed, 15414 insertions(+), 390 deletions(-)
create mode 100644 Documentation/filesystems/caching/backend-api.txt
create mode 100644 Documentation/filesystems/caching/cachefiles.txt
create mode 100644 Documentation/filesystems/caching/fscache.txt
create mode 100644 Documentation/filesystems/caching/netfs-api.txt
create mode 100644 Documentation/filesystems/caching/object.txt
create mode 100644 Documentation/filesystems/caching/operations.txt
create mode 100644 Documentation/slow-work.txt
create mode 100644 fs/cachefiles/Kconfig
create mode 100644 fs/cachefiles/Makefile
create mode 100644 fs/cachefiles/bind.c
create mode 100644 fs/cachefiles/daemon.c
create mode 100644 fs/cachefiles/interface.c
create mode 100644 fs/cachefiles/internal.h
create mode 100644 fs/cachefiles/key.c
create mode 100644 fs/cachefiles/main.c
create mode 100644 fs/cachefiles/namei.c
create mode 100644 fs/cachefiles/proc.c
create mode 100644 fs/cachefiles/rdwr.c
create mode 100644 fs/cachefiles/security.c
create mode 100644 fs/cachefiles/xattr.c
create mode 100644 fs/fscache/Kconfig
create mode 100644 fs/fscache/Makefile
create mode 100644 fs/fscache/cache.c
create mode 100644 fs/fscache/cookie.c
create mode 100644 fs/fscache/fsdef.c
create mode 100644 fs/fscache/histogram.c
create mode 100644 fs/fscache/internal.h
create mode 100644 fs/fscache/main.c
create mode 100644 fs/fscache/netfs.c
create mode 100644 fs/fscache/object.c
create mode 100644 fs/fscache/operation.c
create mode 100644 fs/fscache/page.c
create mode 100644 fs/fscache/proc.c
create mode 100644 fs/fscache/stats.c
create mode 100644 fs/nfs/fscache-index.c
create mode 100644 fs/nfs/fscache.c
create mode 100644 fs/nfs/fscache.h
create mode 100644 include/linux/fscache-cache.h
create mode 100644 include/linux/fscache.h
create mode 100644 include/linux/slow-work.h
create mode 100644 kernel/slow-work.c

---
These patches add local caching for network filesystems such as NFS. To give a
really quick overview of the way the facility works:

+---------+
| |
| NFS |--+
| | |
+---------+ | +----------+
| | |
+---------+ +-->| |
| | | |
| AFS |----->| FS-Cache |
| | | |--+
+---------+ +-->| | |
| | | | +--------------+ +--------------+
+---------+ | +----------+ | | | | |
| | | +-->| CacheFiles |-->| Ext3 |
| ISOFS |--+ | /var/cache | | /dev/sda6 |
| | +--------------+ +--------------+
+---------+

(1) NFS, say, asks FS-Cache to store/retrieve data for it;

(2) FS-Cache asks the cache backend, in this case CacheFiles to honour the
operation;

(3) CacheFiles 'opens' a file in a mounted filesystem, say Ext3, and does read
and write operations of a sort on it;

(4) Ext3 decides how the cache data is laid out on disk - CacheFiles just
attempts to use one sparse file per netfs inode.

(5) If NFS asks for data from the cache, but the file has a hole in it, NFS
falls back to asking the server. The data obtained from the server is
then written over the hole in the file.

To look at it another way:

+---------+
| |
| Server |
| |
+---------+
| NETWORK
~~~~~|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
| +----------+
V | |
+---------+ | |
| | | |
| NFS |----->| FS-Cache |
| | | |--+
+---------+ | | | +--------------+ +--------------+
| | | | | | | |
V +----------+ +-->| CacheFiles |-->| Ext3 |
+---------+ | /var/cache | | /dev/sda6 |
| | +--------------+ +--------------+
| VFS | ^ ^
| | | |
+---------+ +--------------+ |
| KERNEL SPACE | |
~~~~~|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~|~~~~~~|~~~~
| USER SPACE | |
V | |
+---------+ +--------------+
| | | |
| Process | | cachefilesd |
| | | |
+---------+ +--------------+

FS-Cache attempts to provide a caching facility to a network filesystem such
that it's transparent to the users of that network filesystem.

The patches can roughly be broken down into a number of sets:

(*) 01-slow-work.diff
(*) 02-slow-work-dynamic.diff
(*) 03-slow-work-config.diff
(*) 04-slow-work-doc.diff

A thread pool for (very) slow work items, such as batches of lookup,
mkdir, create and [sg]etxattr calls.

It doesn't make sense to use an ordinary work queue because I want more
than one thread, but I don't want to be limited to 1 thread per CPU.
The work items in question take a long time, most of which is spent
sleeping on I/O. For the duration the worker thread is unable to do
anything else.

These four patches add the basic facility, make it dynamic, make it
configurable and document it.

(*) 05-release-page.diff

Call the page release function after a failed readahead.

(*) 06-fscache-page-flags.diff

Add an extra page flag that FS-Cache then uses to keep track of whether a
page is known by the cache, and to indicate that the cache must be
informed if the page is going to go away. It's an indication to the
netfs that the cache has an interest in this page, where an interest may
be a pointer to it, resources allocated or reserved for it, or I/O in
progress upon it.

Note that the cache doesn't necessarily need to be able to find the netfs
pages, but may have to allocate/pin resources for backing them.

Further note that PG_private may not be used as I want to be able to use
caching with ISOFS eventually, and PG_private is owned by the block
buffer code.

These bits can be otherwise used by any filesystem that doesn't want to
use FS-Cache.

(*) 07-fscache-netfs-api.diff
(*) 08-fscache-backend-api.diff
(*) 09-fscache-kconfig.diff
(*) 10-fscache-proc.diff
(*) 11-fscache-fsdef.diff
(*) 12-fscache-tag-handling.diff
(*) 13-fscache-cache-handling.diff
(*) 14-fscache-cookie-jar.diff
(*) 15-fscache-netfs-reg.diff
(*) 16-fscache-bits.diff
(*) 17-fscache-object.diff
(*) 18-fscache-cookie.diff
(*) 19-fscache-operation.diff
(*) 20-fscache-io.diff

Patches to provide a local caching facility for network filesystems.

FS-Cache is a layer that takes requests from any one of a number of
netfs's and passes them to an appropriate cache, if there is one.
FS-Cache makes operations requested by the netfs transparently
asynchronous where possible.

FS-Cache also protects the netfs against (a) there being no cache, (b)
the cache suffering a fatal I/O error and (c) the cache being removed;
and protects the cache against (d) the netfs uncaching pages that the
cache is using and (e) conflicting operations from the netfs, some of
which may be queued for asynchronous processing.

Five documents in text file format that describe the FS-Cache interface
are added by these patches:

Documentation/filesystems/caching/fscache.txt gives an overview of the
facility and describes the statistical data it makes available.

Documentation/filesystems/caching/netfs-api.txt describes the API by
which a network filesystem would make use of the FS-Cache facility.

Documentation/filesystems/caching/backend-api.txt describes the API that
a cache backend must implement to provide caching services through
FS-Cache.

Documentation/filesystems/caching/object.txt describes the object
management state machine used.

Documentation/filesystems/caching/operations.txt describes the operation
scheduling facility provided and used by FS-Cache that can also be used
by cache backend modules.

The patches provide the following components of the FS-Cache facility:

(07) The netfs API header file and documentation. A netfs can actually
be built and run against just this patch. It won't actually do
anything without the later patches, though, but it will compile.

(08) The cache backend API header file and documentation.

(09) The main selector configuration option, the main module load/unload
hooks and the debugging code declarations. With this patch applied,
it is possible to enable caching in a client netfs, though it won't
actually do anything.

(10) The /proc files for statistics presentation, plus the internal
interfaces for driving it.

(11) The top level index definition.

(12) Cache reference tag handling.

(13) Cache (un)registration and error handling.

(14) Cookie (de)allocator and initialisation.

(15) Netfs (un)registration handling. This is partly usable. Without a
later patch, however, a cookie will be leaked from unregistration.

(16) Bit waiting utility functions.

(17) The object management state machine implementation and
documentation.

(18) Implementation of the cookie management part of the netfs API. With
this, it's possible for netfs's to actually be granted cookies and
to release them without error.

(19) Cache I/O operation scheduler and documentation.

(20) Implementation of the data I/O part of the netfs API.

(*) 21-cachefiles-monitor.diff
(*) 22-cachefiles-export.diff
(*) 23-cachefiles.diff

Patches to provide a local cache in a directory of an already mounted
filesystem.

The latter patch adds a document in text file format that describes the
CacheFiles cache backend and gives instructions on how it is set up and
used. This will be Documentation/filesystems/caching/cachefiles.txt when
the patch is applied.

(*) 24-afs-fscache.diff

Patches to provide AFS with local caching.

(*) 25-nfs-comment.diff
(*) 26-nfs-fscache-option.diff
(*) 27-nfs-fscache-kconfig.diff
(*) 28-nfs-fscache-top-index.diff
(*) 29-nfs-fscache-server-obj.diff
(*) 30-nfs-fscache-super-obj.diff
(*) 31-nfs-fscache-inode-obj.diff
(*) 32-nfs-fscache-use-inode.diff
(*) 33-nfs-fscache-invalidate-pages.diff
(*) 34-nfs-fscache-iostats.diff
(*) 35-nfs-fscache-page-management.diff
(*) 36-nfs-fscache-read-context.diff
(*) 37-nfs-fscache-read-fallback.diff
(*) 38-nfs-fscache-read-from-cache.diff
(*) 39-nfs-fscache-store-to-cache.diff
(*) 40-nfs-fscache-display.diff
(*) 41-nfs-fscache-mount.diff

Patches to provide NFS with local caching.

I've been testing these patches by throwing batches of eight parallel "tar cf"
commands across three different 350MB NFS-based kernel trees (3 tars on first
tree, 3 on second, 2 on third), sometimes with one or more of the trees
preloaded into the cache. The complete working data set does not fit into the
RAM of my test machine, so even three tars that can be entirely satisfied from
the cache may have to reread everything from disk.

I've also been running tars against AFS mounted kernel trees.

--
A tarball of the patches is available at:

http://people.redhat.com/~dhowells/fscache/patches/nfs+fscache-48.tar.bz2

This builds on top of Linus's current kernel.

The code can also be obtained by GIT from:

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

tagged as 'fscache-48'.

To use this version of CacheFiles, the cachefilesd-0.9 is also required. It
is available as an SRPM:

http://people.redhat.com/~dhowells/fscache/cachefilesd-0.9-1.fc7.src.rpm

Or as individual bits:

http://people.redhat.com/~dhowells/fscache/cachefilesd-0.9.tar.bz2
http://people.redhat.com/~dhowells/fscache/cachefilesd.fc
http://people.redhat.com/~dhowells/fscache/cachefilesd.if
http://people.redhat.com/~dhowells/fscache/cachefilesd.te
http://people.redhat.com/~dhowells/fscache/cachefilesd.spec

The .fc, .if and .te files are for manipulating SELinux.
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