From: David Sterba <dsterba@suse.cz>
To: Omar Sandoval <osandov@osandov.com>
Cc: linux-btrfs@vger.kernel.org, kernel-team@fb.com,
Nikolay Borisov <nborisov@suse.com>
Subject: Re: [PATCH 2/9] btrfs: remove dead snapshot-aware defrag code
Date: Tue, 10 Dec 2019 18:22:42 +0100 [thread overview]
Message-ID: <20191210172242.GD3929@twin.jikos.cz> (raw)
In-Reply-To: <e8079362b1884b5f71ebe839f01ab8492c2d5d2e.1575336815.git.osandov@fb.com>
On Mon, Dec 02, 2019 at 05:34:18PM -0800, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
>
> Snapshot-aware defrag has been disabled since commit 8101c8dbf624
> ("Btrfs: disable snapshot aware defrag for now") almost 6 years ago.
> Let's remove the dead code. If someone is up to the task of bringing it
> back, they can dig it up from git.
While I usually stand against code deletionists, in this case I will not
and apply the patch. This is a good example how not to implement
features or do post-merge stabilization. There were runtime problems
with defrag on heavily referenced extents (many snapshots) so this was
the main reason to disable it. There's a patchset from Josef from 2014
bitrotting in some of his trees that was supposed to fix it but this
hasn't happen.
Defrag has been known to break reflinks, from what I've heared some
users want that behaviour while others not. So this would be good to
make selectable on the defrag ioctl level. This is a broader task and
from brief look I haven't seen an easy way how to wire that to the
current ioctl. Which means a deeper analysis and design needs to happen
first.
next prev parent reply other threads:[~2019-12-10 17:23 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-03 1:34 [PATCH 0/9] btrfs: miscellaneous cleanups Omar Sandoval
2019-12-03 1:34 ` [PATCH 1/9] btrfs: get rid of trivial __btrfs_lookup_bio_sums() wrappers Omar Sandoval
2019-12-03 8:36 ` Johannes Thumshirn
2019-12-10 17:12 ` David Sterba
2019-12-10 18:24 ` Omar Sandoval
2019-12-10 18:26 ` David Sterba
2019-12-10 18:37 ` [PATCH] btrfs: get rid of at_offset parameter to btrfs_lookup_bio_sums() Omar Sandoval
2019-12-03 1:34 ` [PATCH 2/9] btrfs: remove dead snapshot-aware defrag code Omar Sandoval
2019-12-03 8:38 ` Johannes Thumshirn
2019-12-10 17:22 ` David Sterba [this message]
2019-12-03 1:34 ` [PATCH 3/9] btrfs: make btrfs_ordered_extent naming consistent with btrfs_file_extent_item Omar Sandoval
2019-12-03 9:51 ` Johannes Thumshirn
2019-12-10 18:22 ` David Sterba
2019-12-10 18:32 ` Omar Sandoval
2019-12-10 18:48 ` David Sterba
2019-12-03 1:34 ` [PATCH 4/9] btrfs: remove unnecessary pg_offset assignments in __extent_writepage() Omar Sandoval
2019-12-03 12:59 ` Johannes Thumshirn
2019-12-03 1:34 ` [PATCH 5/9] btrfs: remove trivial goto label " Omar Sandoval
2019-12-03 13:06 ` Johannes Thumshirn
2019-12-03 1:34 ` [PATCH 6/9] btrfs: remove redundant i_size check in __extent_writepage_io() Omar Sandoval
2019-12-10 17:45 ` David Sterba
2019-12-03 1:34 ` [PATCH 7/9] btrfs: drop create parameter to btrfs_get_extent() Omar Sandoval
2019-12-03 7:47 ` Omar Sandoval
2019-12-03 1:34 ` [PATCH 8/9] btrfs: simplify compressed/inline check in __extent_writepage_io() Omar Sandoval
2019-12-03 13:17 ` Johannes Thumshirn
2019-12-03 1:34 ` [PATCH 9/9] btrfs: remove struct find_free_extent.ram_bytes Omar Sandoval
2019-12-03 13:27 ` Johannes Thumshirn
2019-12-03 18:01 ` Omar Sandoval
2019-12-10 18:47 ` [PATCH 0/9] btrfs: miscellaneous cleanups David Sterba
2019-12-10 18:50 ` Omar Sandoval
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