kernel/linux.git/include/linux/exportfs.h, branch v7.0-rc7

nfsd: do not allow exporting of special kernel filesystems

2026-01-29T16:26:30+00:00

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. Therefore, do not allow nfsd to export filesystems with custom ->open() or ->permission() methods. Fixes: b3caba8f7a34a ("pidfs: implement file handle support") Fixes: 5222470b2fbb3 ("nsfs: support file handles") Reviewed-by: Jeff Layton Signed-off-by: Amir Goldstein Link: https://patch.msgid.link/20260129100212.49727-3-amir73il@gmail.com Reviewed-by: Chuck Lever Signed-off-by: Christian Brauner

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

2026-01-29T16:26:30+00:00

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: Jeff Layton Signed-off-by: Amir Goldstein Link: https://patch.msgid.link/20260129100212.49727-2-amir73il@gmail.com Reviewed-by: Chuck Lever Signed-off-by: Christian Brauner

exportfs: Complete kernel-doc for struct export_operations

2026-01-14T15:50:37+00:00

Write down the missing members definitions for struct export_operations, using as a reference the commit messages that created the members. Signed-off-by: André Almeida Link: https://patch.msgid.link/20260112-tonyk-fs_uuid-v1-3-acc1889de772@igalia.com Reviewed-by: Chuck Lever Signed-off-by: Christian Brauner

exportfs: Mark struct export_operations functions at kernel-doc

2026-01-14T15:50:37+00:00

Adding a `@` before the function names make then recognizable as kernel-docs, so they get correctly rendered in the documentation. Even if they are already marked with `@` in the short one-line summary, the kernel-docs will correctly favor the more detailed definition here. Signed-off-by: André Almeida Link: https://patch.msgid.link/20260112-tonyk-fs_uuid-v1-2-acc1889de772@igalia.com Reviewed-by: Chuck Lever Signed-off-by: Christian Brauner

exportfs: Fix kernel-doc output for get_name()

2026-01-14T15:50:37+00:00

Without a space between %NAME_MAX and the plus sign, kernel-doc will output ``NAME_MAX``+1, which scapes the last backtick and make Sphinx format a much larger string as monospaced text. Signed-off-by: André Almeida Link: https://patch.msgid.link/20260112-tonyk-fs_uuid-v1-1-acc1889de772@igalia.com Reviewed-by: Chuck Lever Signed-off-by: Christian Brauner

expfs: Fix exportfs_can_encode_fh() for EXPORT_FH_FID

2025-10-06T12:26:50+00:00

After commit 5402c4d4d200 ("exportfs: require ->fh_to_parent() to encode connectable file handles") we will fail to create non-decodable file handles for filesystems without export operations. Fix it. Fixes: 5402c4d4d200 ("exportfs: require ->fh_to_parent() to encode connectable file handles") Reviewed-by: Christian Brauner Reviewed-by: Amir Goldstein Signed-off-by: Jan Kara

Merge tag 'pull-f_path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2025-10-03T23:32:36+00:00

Pull file->f_path constification from Al Viro: "Only one thing was modifying ->f_path of an opened file - acct(2). Massaging that away and constifying a bunch of struct path * arguments in functions that might be given &file->f_path ends up with the situation where we can turn ->f_path into an anon union of const struct path f_path and struct path __f_path, the latter modified only in a few places in fs/{file_table,open,namei}.c, all for struct file instances that are yet to be opened" * tag 'pull-f_path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (23 commits) Have cc(1) catch attempts to modify ->f_path kernel/acct.c: saner struct file treatment configfs:get_target() - release path as soon as we grab configfs_item reference apparmor/af_unix: constify struct path * arguments ovl_is_real_file: constify realpath argument ovl_sync_file(): constify path argument ovl_lower_dir(): constify path argument ovl_get_verity_digest(): constify path argument ovl_validate_verity(): constify {meta,data}path arguments ovl_ensure_verity_loaded(): constify datapath argument ksmbd_vfs_set_init_posix_acl(): constify path argument ksmbd_vfs_inherit_posix_acl(): constify path argument ksmbd_vfs_kern_path_unlock(): constify path argument ksmbd_vfs_path_lookup_locked(): root_share_path can be const struct path * check_export(): constify path argument export_operations->open(): constify path argument rqst_exp_get_by_name(): constify path argument nfs: constify path argument of __vfs_getattr() bpf...d_path(): constify path argument done_path_create(): constify path argument ...

nsfs: support file handles

2025-09-19T12:26:16+00:00

A while ago we added support for file handles to pidfs so pidfds can be encoded and decoded as file handles. Userspace has adopted this quickly and it's proven very useful. Implement file handles for namespaces as well. A process is not always able to open /proc/self/ns/. That requires procfs to be mounted and for /proc/self/ or /proc/self/ns/ to not be overmounted. However, userspace can always derive a namespace fd from a pidfd. And that always works for a task's own namespace. There's no need to introduce unnecessary behavioral differences between /proc/self/ns/ fds, pidfd-derived namespace fds, and file-handle-derived namespace fds. So namespace file handles are always decodable if the caller is located in the namespace the file handle refers to. This also allows a task to e.g., store a set of file handles to its namespaces in a file on-disk so it can verify when it gets rexeced that they're still valid and so on. This is akin to the pidfd use-case. Or just plainly for namespace comparison reasons where a file handle to the task's own namespace can be easily compared against others. Reviewed-by: Amir Goldstein Signed-off-by: Christian Brauner

export_operations->open(): constify path argument

2025-09-16T01:17:08+00:00

for the method and its sole instance... Reviewed-by: Jan Kara Reviewed-by: Christian Brauner Signed-off-by: Al Viro

docs/vfs: update references to i_mutex to i_rwsem

2025-06-23T10:17:33+00:00

VFS has switched to i_rwsem for ten years now (9902af79c01a: parallel lookups actual switch to rwsem), but the VFS documentation and comments still has references to i_mutex. Signed-off-by: Junxuan Liao Link: https://lore.kernel.org/72223729-5471-474a-af3c-f366691fba82@cs.wisc.edu Signed-off-by: Christian Brauner