Re: [RFC PATCH v10 00/16] Online(inband) data deduplication

From: Martin Steigerwald <Martin@lichtvoll.de>
To: bo.li.liu@oracle.com
Cc: linux-btrfs@vger.kernel.org,
	Andrea Gelmini <andrea.gelmini@linux.it>,
	Marcel Ritter <ritter.marcel@gmail.com>,
	Christian Robert <christian.robert@polymtl.ca>,
	alanqk@gmail.com, Konstantinos Skarlatos <k.skarlatos@gmail.com>,
	David Sterba <dsterba@suse.cz>, Josef Bacik <jbacik@fb.com>,
	Chris Mason <clm@fb.com>
Subject: Re: [RFC PATCH v10 00/16] Online(inband) data deduplication
Date: Fri, 11 Apr 2014 11:28:48 +0200	[thread overview]
Message-ID: <4758484.vdooYxqCmI@merkaba> (raw)
In-Reply-To: <20140410155520.GB23295@localhost.localdomain>

Hi Liu,

Am Donnerstag, 10. April 2014, 23:55:21 schrieb Liu Bo:
> Hi,
> 
> Just FYI, these patches are also available on the following site,
> 
> kernel:
> https://github.com/liubogithub/btrfs-work.git dedup-on-3.14-linux
> 
> progs:
> https://github.com/liubogithub/btrfs-progs.git dedup

I bet its good to only test it with test data so far or would you consider it 
safe enough to test on production data already?

Fortunately since I added that additional mSATA SSD I have some spare storage 
to put some test setup into.

Thanks,
Martin

> thanks,
> -liubo
> 
> On Thu, Apr 10, 2014 at 11:48:30AM +0800, Liu Bo wrote:
> > Hello,
> > 
> > This the 10th attempt for in-band data dedupe, based on Linux _3.14_
> > kernel.
> > 
> > Data deduplication is a specialized data compression technique for
> > eliminating duplicate copies of repeating data.[1]
> > 
> > This patch set is also related to "Content based storage" in project
> > ideas[2], it introduces inband data deduplication for btrfs and
> > dedup/dedupe is for short.
> > 
> > * PATCH 1 is a speed-up improvement, which is about dedup and quota.
> > 
> > * PATCH 2-5 is the preparation work for dedup implementation.
> > 
> > * PATCH 6 shows how we implement dedup feature.
> > 
> > * PATCH 7 fixes a backref walking bug with dedup.
> > 
> > * PATCH 8 fixes a free space bug of dedup extents on error handling.
> > 
> > * PATCH 9 adds the ioctl to control dedup feature.
> > 
> > * PATCH 10 targets delayed refs' scalability problem of deleting refs,
> > which is> 
> >   uncovered by the dedup feature.
> > 
> > * PATCH 11-16 fixes bugs of dedupe including race bug, deadlock, abnormal
> > 
> >   transaction abortion and crash.
> > 
> > * btrfs-progs patch(PATCH 17) offers all details about how to control the
> > 
> >   dedup feature on progs side.
> > 
> > I've tested this with xfstests by adding a inline dedup 'enable & on' in
> > xfstests' mount and scratch_mount.
> > 
> > 
> > ***NOTE***
> > Known bugs:
> > * Mounting with options "flushoncommit" and enabling dedupe feature will
> > end up> 
> >   with _deadlock_.
> > 
> > TODO:
> > * a bit-to-bit comparison callback.
> > 
> > All comments are welcome!
> > 
> > 
> > [1]: http://en.wikipedia.org/wiki/Data_deduplication
> > [2]:
> > https://btrfs.wiki.kernel.org/index.php/Project_ideas#Content_based_stora
> > ge
> > 
> > v10:
> > - fix a typo in the subject line.
> > - update struct 'btrfs_ioctl_dedup_args' in the kernel side to fix
> > 
> >   'Inappropriate ioctl for device'.
> > 
> > v9:
> > - fix a deadlock and a crash reported by users.
> > - fix the metadata ENOSPC problem with dedup again.
> > 
> > v8:
> > - fix the race crash of dedup ref again.
> > - fix the metadata ENOSPC problem with dedup.
> > 
> > v7:
> > - rebase onto the lastest btrfs
> > - break a big patch into smaller ones to make reviewers happy.
> > - kill mount options of dedup and use ioctl method instead.
> > - fix two crash due to the special dedup ref
> > 
> > For former patch sets:
> > v6: http://thread.gmane.org/gmane.comp.file-systems.btrfs/27512
> > v5: http://thread.gmane.org/gmane.comp.file-systems.btrfs/27257
> > v4: http://thread.gmane.org/gmane.comp.file-systems.btrfs/25751
> > v3: http://comments.gmane.org/gmane.comp.file-systems.btrfs/25433
> > v2: http://comments.gmane.org/gmane.comp.file-systems.btrfs/24959
> > 
> > Liu Bo (16):
> >   Btrfs: disable qgroups accounting when quota_enable is 0
> >   Btrfs: introduce dedup tree and relatives
> >   Btrfs: introduce dedup tree operations
> >   Btrfs: introduce dedup state
> >   Btrfs: make ordered extent aware of dedup
> >   Btrfs: online(inband) data dedup
> >   Btrfs: skip dedup reference during backref walking
> >   Btrfs: don't return space for dedup extent
> >   Btrfs: add ioctl of dedup control
> >   Btrfs: improve the delayed refs process in rm case
> >   Btrfs: fix a crash of dedup ref
> >   Btrfs: fix deadlock of dedup work
> >   Btrfs: fix transactin abortion in __btrfs_free_extent
> >   Btrfs: fix wrong pinned bytes in __btrfs_free_extent
> >   Btrfs: use total_bytes instead of bytes_used for global_rsv
> >   Btrfs: fix dedup enospc problem
> >  
> >  fs/btrfs/backref.c           |   9 +
> >  fs/btrfs/ctree.c             |   2 +-
> >  fs/btrfs/ctree.h             |  86 ++++++
> >  fs/btrfs/delayed-ref.c       |  26 +-
> >  fs/btrfs/delayed-ref.h       |   3 +
> >  fs/btrfs/disk-io.c           |  37 +++
> >  fs/btrfs/extent-tree.c       | 235 +++++++++++++---
> >  fs/btrfs/extent_io.c         |  22 +-
> >  fs/btrfs/extent_io.h         |  16 ++
> >  fs/btrfs/file-item.c         | 244 +++++++++++++++++
> >  fs/btrfs/inode.c             | 635
> >  ++++++++++++++++++++++++++++++++++++++----- fs/btrfs/ioctl.c            
> >  | 167 ++++++++++++
> >  fs/btrfs/ordered-data.c      |  44 ++-
> >  fs/btrfs/ordered-data.h      |  13 +-
> >  fs/btrfs/qgroup.c            |   3 +
> >  fs/btrfs/relocation.c        |   3 +
> >  fs/btrfs/transaction.c       |  41 +++
> >  fs/btrfs/transaction.h       |   1 +
> >  include/trace/events/btrfs.h |   3 +-
> >  include/uapi/linux/btrfs.h   |  12 +
> >  20 files changed, 1471 insertions(+), 131 deletions(-)

-- 
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
GPG: 03B0 0D6C 0040 0710 4AFA  B82F 991B EAAC A599 84C7