From 4a530a7c751d27f9dbd70b7fc45670cd11713b13 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Fri, 11 Oct 2024 11:00:21 +0200 Subject: fs: prepare for "explicit connectable" file handles We would like to use the high 16bit of the handle_type field to encode file handle traits, such as "connectable". In preparation for this change, make sure that filesystems do not return a handle_type value with upper bits set and that the open_by_handle_at(2) syscall rejects these handle types. Signed-off-by: Amir Goldstein Link: https://lore.kernel.org/r/20241011090023.655623-2-amir73il@gmail.com Fixes: 570df4e9c23f ("ceph: snapshot nfs re-export") Acked-by: Reviewed-by: Jan Kara Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- include/linux/exportfs.h | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'include') diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h index 893a1d21dc1c..5e14d4500a75 100644 --- a/include/linux/exportfs.h +++ b/include/linux/exportfs.h @@ -160,6 +160,17 @@ struct fid { #define EXPORT_FH_FID 0x2 /* File handle may be non-decodeable */ #define EXPORT_FH_DIR_ONLY 0x4 /* Only decode file handle for a directory */ +/* + * Filesystems use only lower 8 bits of file_handle type for fid_type. + * name_to_handle_at() uses upper 16 bits of type as user flags to be + * interpreted by open_by_handle_at(). + */ +#define FILEID_USER_FLAGS_MASK 0xffff0000 +#define FILEID_USER_FLAGS(type) ((type) & FILEID_USER_FLAGS_MASK) + +/* Flags supported in encoded handle_type that is exported to user */ +#define FILEID_VALID_USER_FLAGS (0) + /** * struct export_operations - for nfsd to communicate with file systems * @encode_fh: encode a file handle fragment from a dentry -- cgit v1.2.3