[PATCHSET,v11,00/12] xfs: name-value xattr lookups

Message

Darrick J. Wong April 6, 2023, 7:13 p.m. UTC

Hi all,

Directory parent pointers are stored as namespaced extended attributes
of a file.  Because parent pointers can consume up to 267 bytes of
space and xattr names are 255 bytes at most, we cannot use the usual
attr name lookup functions to find a parent pointer.  This is solvable
by introducing a new lookup mode that checks both the name and the
value of the xattr.

Therefore, introduce this new lookup mode.  Because all parent pointer
updates are logged, we must extend the xattr logging code to capture the
VLOOKUP variants, and restore them when recovering logged operations.
These new log formats are protected by the sb_incompat PARENT flag, so
they do not need a separate log_incompat feature flag.

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.
kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=pptrs-attr-nvlookups

xfsprogs git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfsprogs-dev.git/log/?h=pptrs-attr-nvlookups
---
 fs/xfs/libxfs/xfs_attr.c       |   57 +++++--
 fs/xfs/libxfs/xfs_attr.h       |    9 +
 fs/xfs/libxfs/xfs_attr_leaf.c  |   45 ++++-
 fs/xfs/libxfs/xfs_da_btree.h   |   10 +
 fs/xfs/libxfs/xfs_log_format.h |   30 +++
 fs/xfs/xfs_attr_item.c         |  347 ++++++++++++++++++++++++++++++++++------
 fs/xfs/xfs_attr_item.h         |    2 
 fs/xfs/xfs_xattr.c             |    5 +
 8 files changed, 425 insertions(+), 80 deletions(-)