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From: Christoph Hellwig <hch@lst.de>
To: linux-xfs@vger.kernel.org
Subject: COW improvements and always_cow support V2
Date: Mon, 19 Nov 2018 14:46:10 +0100	[thread overview]
Message-ID: <20181119134619.16812-1-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.

Changes since v1:
 - make delalloc and unwritten extent conversions simpler and more robust
 - add a few additional cleanups
 - support all fallocate modes but actual preallocation
 - rebase on top of a fix from Brian (which is included as first patch
   to make the patch set more usable)

             reply	other threads:[~2018-11-20  0:10 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-19 13:46 Christoph Hellwig [this message]
2018-11-19 13:46 ` [PATCH 1/9] xfs: fix shared extent data corruption due to missing cow reservation Christoph Hellwig
2018-11-19 13:46 ` [PATCH 2/9] xfs: handle -EAGAIN from xfs_iomap_write_allocate Christoph Hellwig
2018-11-19 13:46 ` [PATCH 3/9] xfs: avoid an extent tree lookup in xfs_iomap_write_allocate Christoph Hellwig
2018-11-19 13:46 ` [PATCH 4/9] xfs: make xfs_bmbt_to_iomap more useful Christoph Hellwig
2018-11-19 13:46 ` [PATCH 5/9] xfs: don't use delalloc extents for COW on files with extsize hints Christoph Hellwig
2018-11-19 13:46 ` [PATCH 6/9] xfs: merge COW handling into xfs_file_iomap_begin_delay Christoph Hellwig
2018-11-19 13:46 ` [PATCH 7/9] xfs: report IOMAP_F_SHARED from xfs_file_iomap_begin_delay Christoph Hellwig
2018-11-19 13:46 ` [PATCH 8/9] xfs: make COW fork unwritten extent conversions more robust Christoph Hellwig
2018-11-19 13:46 ` [PATCH 9/9] xfs: introduce an always_cow mode Christoph Hellwig
2018-11-25 13:39 ` COW improvements and always_cow support V2 Chandan Rajendra
2018-11-26 11:42   ` Chandan Rajendra
2018-11-28  7:52     ` Christoph Hellwig

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