[PATCHSET,0/1] fstests: defragment free space

Message

Darrick J. Wong Dec. 30, 2022, 10:21 p.m. UTC

Hi all,

These patches contain experimental code to enable userspace to defragment
the free space in a filesystem.  Two purposes are imagined for this
functionality: clearing space at the end of a filesystem before
shrinking it, and clearing free space in anticipation of making a large
allocation.

The first patch adds a new fallocate mode that allows userspace to
allocate free space from the filesystem into a file.  The goal here is
to allow the filesystem shrink process to prevent allocation from a
certain part of the filesystem while a free space defragmenter evacuates
all the files from the doomed part of the filesystem.

The second patch amends the online repair system to allow the sysadmin
to forcibly rebuild metadata structures, even if they're not corrupt.
Without adding an ioctl to move metadata btree blocks, this is the only
way to dislodge metadata.

If you're going to start using this mess, you probably ought to just
pull from my git trees, which are linked below.

This is an extraordinary way to destroy everything.  Enjoy!
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=defrag-freespace

xfsprogs git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfsprogs-dev.git/log/?h=defrag-freespace

fstests git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfstests-dev.git/log/?h=defrag-freespace
---
 common/rc          |    2 +
 tests/xfs/1400     |   57 +++++++++++++++++++++++++++++++++++++
 tests/xfs/1400.out |    2 +
 tests/xfs/1401     |   80 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 tests/xfs/1401.out |    2 +
 5 files changed, 142 insertions(+), 1 deletion(-)
 create mode 100755 tests/xfs/1400
 create mode 100644 tests/xfs/1400.out
 create mode 100755 tests/xfs/1401
 create mode 100644 tests/xfs/1401.out