[PATCH v1 00/17] fuse: extend passthrough to inode operations

[Joanne Koong <joannelkoong@gmail.com>]

This series extends fuse passthrough to support inode operations (getattr,
setattr), directory readdir, and kernel-initiated open on backing files.

The existing FUSE_PASSTHROUGH mode attaches a backing file to a fuse inode
only when a passthrough file is open. This series introduces
FUSE_PASSTHROUGH_INO, a stricter mode requiring one-to-one inode number
mapping, which allows attaching a backing file for the lifetime of the fuse
inode.

Future work includes passthrough for additional operations (rename, unlink,
readdirplus) and full subtree passthrough, which will be part of a separate
series.

Patches 1-7 are from Amir from his git tree in [1]. There were a few
modifications made (removed separate FUSE_PASSTHROUGH_OP_STATX op,
modified fuse_kstat_to_attr() - the full diff of changes is in [2]); if there
are any mistakes, those are mine and not Amir's.

For testing/debugging, this was done using the passthrough_hp server with the
changes from [3]. readdirplus passthrough is not yet implemented, so after an
ls, subsequent operations on listed files will go through the server until
their dentries expire and a fresh lookup sets up passthrough. During
testing/debugging, I avoided ls and accessed files directly.

[1] https://github.com/amir73il/linux/commits/fuse-backing-inode-wip/
[2] https://gist.github.com/joannekoong/1e55f90c355a928eb5fa0ac9972c1d0e
[3] https://github.com/joannekoong/libfuse/commits/extended_passthrough

Amir Goldstein (7):
  fuse: introduce FUSE_PASSTHROUGH_INO mode
  fuse: prepare for passthrough of inode operations
  fuse: prepare for readdir passthrough on directories
  fuse: implement passthrough for readdir
  fuse: prepare for long lived reference on backing file
  fuse: implement passthrough for getattr/statx
  fuse: prepare to setup backing inode passthrough on lookup

Joanne Koong (10):
  fuse: add passthrough ops gating
  fuse: prepare to cache statx attributes from entry replies
  fuse: add struct fuse_entry2_out and helpers for extended entry
    replies
  fuse: add passthrough lookup
  fuse: add passthrough support for entry creation
  fuse: add passthrough support for atomic file creation
  fuse: use passthrough getattr in setattr suid/sgid handling
  fuse: add passthrough setattr
  fuse: add passthrough open
  docs: fuse: document extended passthrough (FUSE_PASSTHROUGH_INO)

 .../filesystems/fuse/fuse-passthrough.rst     | 131 ++++++++
 fs/fuse/backing.c                             |  58 +++-
 fs/fuse/cuse.c                                |   2 +-
 fs/fuse/dir.c                                 | 293 +++++++++++++++---
 fs/fuse/file.c                                |  61 +++-
 fs/fuse/fuse_i.h                              | 112 ++++++-
 fs/fuse/inode.c                               |  27 +-
 fs/fuse/iomode.c                              | 114 +++++--
 fs/fuse/passthrough.c                         | 170 +++++++++-
 fs/fuse/readdir.c                             |   5 +-
 include/uapi/linux/fuse.h                     |  33 +-
 11 files changed, 871 insertions(+), 135 deletions(-)

-- 
2.52.0