[PATCH 0/8] btrfs-progs: add subvol list options for sane path behavior

[Omar Sandoval <osandov@osandov.com>]

From: Omar Sandoval <osandov@fb.com>

Hello,

btrfs subvol list's path handling has been a constant source of
confusion for users. None of -o, -a, or the default do what users
expect. This has been broken for a decade; see [1].

This series adds two new options, -O and -A, which do what users
actually want: list subvolumes below a path, or list all subvolumes,
with minimal path shenanigans. This approach is conservative and tries
to maintain backwards compatibility, but it's worth discussing whether
we should instead fix the existing options/default, or more noisily
deprecate the existing options.

One additional benefit of this is that -O can be used by unprivileged
users.

Patch 1 fixes a libbtrfsutil bug I encountered while testing this.
Patches 2 and 3 fix libbtrfsutil's privilege checks to work in user
namespaces. Patches 4 and 5 remove some unused subvol list code. Patch 6
documents and tests the current, insane behavior. Patch 7 converts
subvol list to use libbtrfsutil. This is a revival of one of my old
patches [2], but is much easier now that libbtrfs has been pared down.
Patch 8 adds the new options, including documentation and tests.

Thanks!
Omar

1: https://lore.kernel.org/all/bdd9af61-b408-c8d2-6697-84230b0bcf89@gmail.com/
2: https://lore.kernel.org/all/6492726d6e89bf792627e4431f7ba7691f09c3d2.1518720598.git.osandov@fb.com/

Omar Sandoval (8):
  libbtrfsutil: fix accidentally closing fd passed to subvolume iterator
  libbtrfsutil: don't check for UID 0 in subvolume_info()
  libbtrfsutil: don't check for UID 0 in subvolume iterator
  btrfs-progs: subvol list: remove unused raw layout code
  btrfs-progs: subvol list: remove unused filters
  btrfs-progs: subvol list: document and test actual behavior of paths
  btrfs-progs: subvol list: use libbtrfsutil
  btrfs-progs: subvol list: add sane -O and -A options

 Documentation/btrfs-subvolume.rst             |   37 +-
 cmds/subvolume-list.c                         | 1081 +++++------------
 libbtrfsutil/python/tests/test_subvolume.py   |   18 +
 libbtrfsutil/subvolume.c                      |   50 +-
 .../026-subvolume-list-path-filtering/test.sh |  156 +++
 5 files changed, 565 insertions(+), 777 deletions(-)
 create mode 100755 tests/cli-tests/026-subvolume-list-path-filtering/test.sh

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2.45.2