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From: Christoph Hellwig <hch@lst.de>
To: linux-xfs@vger.kernel.org
Subject: COW improvements and always_cow support
Date: Sat, 10 Nov 2018 12:51:01 +0100	[thread overview]
Message-ID: <20181110115104.30293-1-hch@lst.de> (raw)

Hi all,

this series adds the always_cow mode support after improving our COW
write support a little bit first.

The always_cow mode stresses the COW path a lot, but with a few xfstests
fixups it generall looks good, except for:

 - a few tests that complain about fragmentation, which is rather inherent
   in this mode
 - generic/208 crashing a lot (and generic/095 with 1k block similarly)
   because a COW fork extent has changed under writeback.  As far as I can
   tell this is because nothing prevents another thread from moving a COW
   fork extent to the data fork while we are under writeback.  I'm currently
   fully root causing this and looking into a potential fix
 - xfs/017 crashes occasionally in log recovery because we can't find
   a refcount tree record that we try to free.
   I haven't really fully understood this one yet.

             reply	other threads:[~2018-11-10 21:35 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-10 11:51 Christoph Hellwig [this message]
2018-11-10 11:51 ` [PATCH 1/3] xfs: don't use delalloc extents for COW on files with extsize hints Christoph Hellwig
2018-11-10 11:51 ` [PATCH 2/3] xfs: merge COW handling into xfs_file_iomap_begin_delay Christoph Hellwig
2018-11-10 11:51 ` [PATCH 3/3] xfs: introduce an always_cow mode Christoph Hellwig
2018-11-10 17:47   ` Darrick J. Wong
2018-11-11 16:30     ` Christoph Hellwig
2018-11-12  7:20       ` Christoph Hellwig
2018-11-12  7:26 ` [PATCH 4/3] xfs: make COW fork unwritten extent conversions more robust Christoph Hellwig

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