xfs: restore speculative_cow_prealloc_lifetime sysctl
authorDarrick J. Wong <djwong@kernel.org>
Fri, 12 Feb 2021 17:14:47 +0000 (09:14 -0800)
committerDarrick J. Wong <djwong@kernel.org>
Wed, 24 Feb 2021 18:16:08 +0000 (10:16 -0800)
commit89e0eb8c13bb842e224b27d7e071262cd84717cb
tree9ed5e011f20b241c8e5367968edc0a9db01c4451
parent1cd738b13ae9b29e03d6149f0246c61f76e81fcf
xfs: restore speculative_cow_prealloc_lifetime sysctl

In commit 9669f51de5c0 I tried to get rid of the undocumented cow gc
lifetime knob.  The knob's function was never documented and it now
doesn't really have a function since eof and cow gc have been
consolidated.

Regrettably, xfs/231 relies on it and regresses on for-next.  I did not
succeed at getting far enough through fstests patch review for the fixup
to land in time.

Restore the sysctl knob, document what it did (does?), put it on the
deprecation schedule, and rip out a redundant function.

Fixes: 9669f51de5c0 ("xfs: consolidate the eofblocks and cowblocks workers")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Documentation/admin-guide/xfs.rst
fs/xfs/xfs_sysctl.c