This series adds support for name_to_handle_at() and open_by_handle_at() to io_uring. The idea is for these opcodes to be useful for userspace NFS servers that want to use io_uring. The biggest change since [v1] is that this adds support for attempting non-blocking open_by_handle_at(). When io_uring calls handle_to_path(), it will set a flag to request that the call return -EAGAIN if it cannot complete using cached data. The same holds for the call to do_filp_path_open(). Supporting this for handle_to_path() requires a way to communicate to the filesystem that it should not block in its fh_to_dentry() implementation. This is done with a new flag FILEID_CACHED which is set in the file handle by the VFS. If a filesystem supports this new flag, it will indicate that with a new flag EXPORT_OP_NONBLOCK so that the VFS knows not to call into a filesystem with the FILEID_CACHED flag, when the FS does not know about that flag. Support for the new FILEID_CACHED flag is added for xfs. Thanks to Amir Goldstein for the review comments and suggesting this approach on v1. Testing ======= As in v1, a liburing branch with a test is available at https://github.com/bertschingert/liburing/tree/open_by_handle_at and is run with $ ./test/open_by_handle_at.t v1 -> v2: - rename some new helper functions: - do_name_to_handle_at() -> do_sys_name_to_handle_at() - __do_handle_open() -> do_filp_path_open() - create a union member name_to_handle_flags in struct io_uring_sqe - add new FILEID_CACHED and EXPORT_OP_NONBLOCK flags - attempt non-blocking open_by_handle_at() in io_uring first, rather than always giving up and running in async context - add support for FILEID_CACHED in xfs [v1] https://lore.kernel.org/linux-fsdevel/20250814235431.995876-1-tahbertschinger@xxxxxxxxx/ Thomas Bertschinger (10): fhandle: create helper for name_to_handle_at(2) io_uring: add support for IORING_OP_NAME_TO_HANDLE_AT fhandle: helper for allocating, reading struct file_handle fhandle: create do_filp_path_open() helper fhandle: make do_filp_path_open() take struct open_flags exportfs: allow VFS flags in struct file_handle exportfs: new FILEID_CACHED flag for non-blocking fh lookup io_uring: add __io_open_prep() helper io_uring: add support for IORING_OP_OPEN_BY_HANDLE_AT xfs: add support for non-blocking fh_to_dentry() fs/exportfs/expfs.c | 15 ++- fs/fhandle.c | 156 ++++++++++++++++----------- fs/internal.h | 13 +++ fs/xfs/xfs_export.c | 32 ++++-- fs/xfs/xfs_export.h | 3 +- fs/xfs/xfs_handle.c | 2 +- include/linux/exportfs.h | 34 +++++- include/uapi/linux/io_uring.h | 3 + io_uring/opdef.c | 26 +++++ io_uring/openclose.c | 191 ++++++++++++++++++++++++++++++++-- io_uring/openclose.h | 13 +++ 11 files changed, 405 insertions(+), 83 deletions(-) base-commit: 76eeb9b8de9880ca38696b2fb56ac45ac0a25c6c -- 2.51.0
