Unverified Commit a39162f7 authored by Amir Goldstein's avatar Amir Goldstein Committed by Christian Brauner
Browse files

exportfs: clarify the documentation of open()/permission() expotrfs ops 



pidfs and nsfs recently gained support for encode/decode of file handles
via name_to_handle_at(2)/open_by_handle_at(2).

These special kernel filesystems have custom ->open() and ->permission()
export methods, which nfsd does not respect and it was never meant to be
used for exporting those filesystems by nfsd.

Update kernel-doc comments to express the fact the those methods are for
open_by_handle(2) system only and not compatible with nfsd.

Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Link: https://patch.msgid.link/20260129100212.49727-2-amir73il@gmail.com


Reviewed-by: default avatarChuck Lever <chuck.lever@oracle.com>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent b1353865

include/linux/exportfs.h

+10 −2
Original line number Diff line number Diff line
@@ -200,6 +200,10 @@ struct handle_to_path_ctx { 
 * @get_parent:     find the parent of a given directory

 * @commit_metadata: commit metadata changes to stable storage

 *

 * Methods for open_by_handle(2) syscall with special kernel file systems:

 * @permission:     custom permission for opening a file by handle

 * @open:           custom open routine for opening file by handle

 *

 * See Documentation/filesystems/nfs/exporting.rst for details on how to use

 * this interface correctly and the definition of the flags.

 *
@@ -244,10 +248,14 @@ struct handle_to_path_ctx { 
 *    space cannot be allocated, a %ERR_PTR should be returned.

 *

 * @permission:

 *    Allow filesystems to specify a custom permission function.

 *    Allow filesystems to specify a custom permission function for the

 *    open_by_handle_at(2) syscall instead of the default permission check.

 *    This custom permission function is not respected by nfsd.

 *

 * @open:

 *    Allow filesystems to specify a custom open function.

 *    Allow filesystems to specify a custom open function for the

 *    open_by_handle_at(2) syscall instead of the default file_open_root().

 *    This custom open function is not respected by nfsd.

 *

 * @commit_metadata:

 *    @commit_metadata should commit metadata changes to stable storage.