Konstantin Khlebnikov b9ea25152e page_writeback: clean up mess around cancel_dirty_page()
This patch replaces cancel_dirty_page() with a helper function
account_page_cleaned() which only updates counters.  It's called from
truncate_complete_page() and from try_to_free_buffers() (hack for ext3).
Page is locked in both cases, page-lock protects against concurrent
dirtiers: see commit 2d6d7f982846 ("mm: protect set_page_dirty() from
ongoing truncation").

Delete_from_page_cache() shouldn't be called for dirty pages, they must
be handled by caller (either written or truncated).  This patch treats
final dirty accounting fixup at the end of __delete_from_page_cache() as
a debug check and adds WARN_ON_ONCE() around it.  If something removes
dirty pages without proper handling that might be a bug and unwritten
data might be lost.

Hugetlbfs has no dirty pages accounting, ClearPageDirty() is enough
here.

cancel_dirty_page() in nfs_wb_page_cancel() is redundant.  This is
helper for nfs_invalidate_page() and it's called only in case complete
invalidation.

The mess was started in v2.6.20 after commits 46d2277c796f ("Clean up
and make try_to_free_buffers() not race with dirty pages") and
3e67c0987d75 ("truncate: clear page dirtiness before running
try_to_free_buffers()") first was reverted right in v2.6.20 in commit
ecdfc9787fe5 ("Resurrect 'try_to_free_buffers()' VM hackery"), second in
v2.6.25 commit a2b345642f53 ("Fix dirty page accounting leak with ext3
data=journal").

Custom fixes were introduced between these points.  NFS in v2.6.23, commit
1b3b4a1a2deb ("NFS: Fix a write request leak in nfs_invalidate_page()").
Kludge in __delete_from_page_cache() in v2.6.24, commit 3a6927906f1b ("Do
dirty page accounting when removing a page from the page cache").  Since
v2.6.25 all of them are redundant.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Tejun Heo <tj@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-14 16:49:01 -07:00
..

Lustre Parallel Filesystem Client
=================================

The Lustre file system is an open-source, parallel file system
that supports many requirements of leadership class HPC simulation
environments.
Born from from a research project at Carnegie Mellon University,
the Lustre file system is a widely-used option in HPC.
The Lustre file system provides a POSIX compliant file system interface,
can scale to thousands of clients, petabytes of storage and
hundreds of gigabytes per second of I/O bandwidth.

Unlike shared disk storage cluster filesystems (e.g. OCFS2, GFS, GPFS),
Lustre has independent Metadata and Data servers that clients can access
in parallel to maximize performance.

In order to use Lustre client you will need to download lustre client
tools from
https://downloads.hpdd.intel.com/public/lustre/latest-feature-release/
the package name is lustre-client.

You will need to install and configure your Lustre servers separately.

Mount Syntax
============
After you installed the lustre-client tools including mount.lustre binary
you can mount your Lustre filesystem with:

mount -t lustre mgs:/fsname mnt

where mgs is the host name or ip address of your Lustre MGS(management service)
fsname is the name of the filesystem you would like to mount.


Mount Options
=============

  noflock
	Disable posix file locking (Applications trying to use
	the functionality will get ENOSYS)

  localflock
	Enable local flock support, using only client-local flock
	(faster, for applications that require flock but do not run
	 on multiple nodes).

  flock
	Enable cluster-global posix file locking coherent across all
	client nodes.

  user_xattr, nouser_xattr
	Support "user." extended attributes (or not)

  user_fid2path, nouser_fid2path
	Enable FID to path translation by regular users (or not)

  checksum, nochecksum
	Verify data consistency on the wire and in memory as it passes
	between the layers (or not).

  lruresize, nolruresize
	Allow lock LRU to be controlled by memory pressure on the server
	(or only 100 (default, controlled by lru_size proc parameter) locks
	 per CPU per server on this client).

  lazystatfs, nolazystatfs
	Do not block in statfs() if some of the servers are down.

  32bitapi
	Shrink inode numbers to fit into 32 bits. This is necessary
	if you plan to reexport Lustre filesystem from this client via
	NFSv4.

  verbose, noverbose
	Enable mount/umount console messages (or not)

More Information
================
You can get more information at
OpenSFS website: http://lustre.opensfs.org/about/
Intel HPDD wiki: https://wiki.hpdd.intel.com

Out of tree Lustre client and server code is available at:
http://git.whamcloud.com/fs/lustre-release.git

Latest binary packages:
http://lustre.opensfs.org/download-lustre/