Re: [PATCH 00/19] libfuse: Add support for synchronous init

["Darrick J. Wong" <djwong@kernel.org>]

On Mon, Mar 23, 2026 at 06:44:55PM +0100, Bernd Schubert wrote:
> I'm taking Darricks example here and posting API changing libfuse
> changes to linux-fsdevel. We should consider to create a fuse

O^o

> specific list if that is too much. The existing
> fuse-devel@lists.sourceforge.net is rather hopeless due to lack
> of spam filtering.

Yeah, it'd be nice to have a separate list, fsdevel is drinking from the
firehose.

> The first few patches in this series are just preparation, after that
> follow the important parts:
> 
> 1) New daemonize API, see that commit for details. In short, the existing
> fuse_daemonize() was not sufficient for complex daemons and is impossible
> to use with sync-init and the current way to start fuse-io-uring ring
> threads.
> 
> 2) Support for privileged daemons, still rather straight forward, but
> requires the startup of a worker thread that handles requests until
> mount is complete.
> 
> 3) Privileged daemons - requirement is to update the API with fusermount,
> because fuse_session_mount_new_api() needs to obtain the /dev/fuse file
> descriptor, then start the worker thread with that fd and then continue
> the actual mount through fusermount.

Heh, I'll get back to the last part tomorrow.

--D

> To: linux-fsdevel@vger.kernel.org
> Cc: Miklos Szeredi <miklos@szeredi.hu>
> Cc: Joanne Koong <joannelkoong@gmail.com>
> Cc: Darrick J. Wong <djwong@kernel.org>
> Joanne Koong <joannelkoong@gmail.com>
> 
> Signed-off-by: Bernd Schubert <bernd@bsbernd.com>
> ---
> Bernd Schubert (19):
>       ci-build: Add environment logging
>       Add 'STRCPY' to the checkpatch ignore option
>       checkpatch.pl: Add _Atomic to $Attribute patttern
>       Add a new daemonize API
>       Sync fuse_kernel.h with linux-6.18
>       mount.c: Split fuse_mount_sys to prepare privileged sync FUSE_INIT
>       Add FUSE_MOUNT_FALLBACK_NEEDED define for -2 mount errors
>       Refactor mount code / move common functions to mount_util.c
>       Move mount flags to mount_i.h
>       conftest.py: Add more valgrind filter patterns
>       Add support for the new linux mount API
>       fuse mount: Support synchronous FUSE_INIT (privileged daemon)
>       Add fuse_session_set_debug() to enable debug output without foreground
>       Move more generic mount code to mount_util.{c,h}
>       Split the fusermount do_mount function
>       fusermount: Refactor extract_x_options
>       Make fusermount work bidirectional for sync init
>       New mount API: Filter out "user="
>       Add support for sync-init of unprivileged daemons
> 
>  .github/workflows/checkpatch.yml |   2 +-
>  checkpatch.pl                    |   3 +-
>  doc/README.daemonize             | 186 +++++++++++
>  doc/README.fusermount            | 359 +++++++++++++++++++++
>  doc/README.mount                 |  86 +++++
>  doc/README.sync-init             | 184 +++++++++++
>  example/passthrough_hp.cc        |  18 +-
>  include/fuse_daemonize.h         |  71 +++++
>  include/fuse_kernel.h            |   1 +
>  include/fuse_lowlevel.h          |  24 ++
>  include/meson.build              |   3 +-
>  lib/fuse_daemonize.c             | 292 +++++++++++++++++
>  lib/fuse_i.h                     |  27 +-
>  lib/fuse_lowlevel.c              | 342 +++++++++++++++++++-
>  lib/fuse_versionscript           |   4 +
>  lib/helper.c                     |  13 +-
>  lib/meson.build                  |   6 +-
>  lib/mount.c                      | 380 +++++++++++++++-------
>  lib/mount_bsd.c                  |   1 +
>  lib/mount_common_i.h             |  29 ++
>  lib/mount_fsmount.c              | 417 ++++++++++++++++++++++++
>  lib/mount_i_linux.h              |  87 +++++
>  lib/mount_util.c                 |  34 ++
>  lib/mount_util.h                 |  11 +
>  meson.build                      |  19 +-
>  test/ci-build.sh                 |  16 +
>  test/conftest.py                 |   7 +-
>  test/test_want_conversion.c      |   1 +
>  util/fusermount.c                | 671 +++++++++++++++++++++++++++++++--------
>  util/meson.build                 |   2 +-
>  30 files changed, 3024 insertions(+), 272 deletions(-)
> ---
> base-commit: 9eba0f3c9e8b5af7b252093bb6f81f086bb35563
> change-id: 20260323-fuse-init-before-mount-8f5b09a1acf1
> 
> Best regards,
> -- 
> Bernd Schubert <bernd@bsbernd.com>
> 
>