From 5e7fa6bfa9b5ced6868fc652d5c40fe0eac154d9 Mon Sep 17 00:00:00 2001 From: André Almeida Date: Mon, 12 Jan 2026 22:51:24 -0300 Subject: exportfs: Fix kernel-doc output for get_name() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 --- include/linux/exportfs.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/exportfs.h') diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h index f0cf2714ec52..599ea86363e1 100644 --- a/include/linux/exportfs.h +++ b/include/linux/exportfs.h @@ -234,7 +234,7 @@ struct handle_to_path_ctx { * get_name: * @get_name should find a name for the given @child in the given @parent * directory. The name should be stored in the @name (with the - * understanding that it is already pointing to a %NAME_MAX+1 sized + * understanding that it is already pointing to a %NAME_MAX + 1 sized * buffer. get_name() should return %0 on success, a negative error code * or error. @get_name will be called without @parent->i_rwsem held. * -- cgit v1.2.3 From fc76b5968a435894062ad4160c2e81c32cc4972e Mon Sep 17 00:00:00 2001 From: André Almeida Date: Mon, 12 Jan 2026 22:51:25 -0300 Subject: exportfs: Mark struct export_operations functions at kernel-doc MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 --- include/linux/exportfs.h | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) (limited to 'include/linux/exportfs.h') diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h index 599ea86363e1..bed370b9f906 100644 --- a/include/linux/exportfs.h +++ b/include/linux/exportfs.h @@ -203,7 +203,7 @@ struct handle_to_path_ctx { * See Documentation/filesystems/nfs/exporting.rst for details on how to use * this interface correctly. * - * encode_fh: + * @encode_fh: * @encode_fh should store in the file handle fragment @fh (using at most * @max_len bytes) information that can be used by @decode_fh to recover the * file referred to by the &struct dentry @de. If @flag has CONNECTABLE bit @@ -215,7 +215,7 @@ struct handle_to_path_ctx { * greater than @max_len*4 bytes). On error @max_len contains the minimum * size(in 4 byte unit) needed to encode the file handle. * - * fh_to_dentry: + * @fh_to_dentry: * @fh_to_dentry is given a &struct super_block (@sb) and a file handle * fragment (@fh, @fh_len). It should return a &struct dentry which refers * to the same file that the file handle fragment refers to. If it cannot, @@ -227,29 +227,29 @@ struct handle_to_path_ctx { * created with d_alloc_root. The caller can then find any other extant * dentries by following the d_alias links. * - * fh_to_parent: + * @fh_to_parent: * Same as @fh_to_dentry, except that it returns a pointer to the parent * dentry if it was encoded into the filehandle fragment by @encode_fh. * - * get_name: + * @get_name: * @get_name should find a name for the given @child in the given @parent * directory. The name should be stored in the @name (with the * understanding that it is already pointing to a %NAME_MAX + 1 sized * buffer. get_name() should return %0 on success, a negative error code * or error. @get_name will be called without @parent->i_rwsem held. * - * get_parent: + * @get_parent: * @get_parent should find the parent directory for the given @child which * is also a directory. In the event that it cannot be found, or storage * space cannot be allocated, a %ERR_PTR should be returned. * - * permission: + * @permission: * Allow filesystems to specify a custom permission function. * - * open: + * @open: * Allow filesystems to specify a custom open function. * - * commit_metadata: + * @commit_metadata: * @commit_metadata should commit metadata changes to stable storage. * * Locking rules: -- cgit v1.2.3 From 7a6f811e2c06d656996776771f0498df129a0cc2 Mon Sep 17 00:00:00 2001 From: André Almeida Date: Mon, 12 Jan 2026 22:51:26 -0300 Subject: exportfs: Complete kernel-doc for struct export_operations MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 --- include/linux/exportfs.h | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) (limited to 'include/linux/exportfs.h') diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h index bed370b9f906..262e24d83313 100644 --- a/include/linux/exportfs.h +++ b/include/linux/exportfs.h @@ -201,7 +201,7 @@ struct handle_to_path_ctx { * @commit_metadata: commit metadata changes to stable storage * * See Documentation/filesystems/nfs/exporting.rst for details on how to use - * this interface correctly. + * this interface correctly and the definition of the flags. * * @encode_fh: * @encode_fh should store in the file handle fragment @fh (using at most @@ -252,6 +252,19 @@ struct handle_to_path_ctx { * @commit_metadata: * @commit_metadata should commit metadata changes to stable storage. * + * @get_uuid: + * Get a filesystem unique signature exposed to clients. + * + * @map_blocks: + * Map and, if necessary, allocate blocks for a layout. + * + * @commit_blocks: + * Commit blocks in a layout once the client is done with them. + * + * @flags: + * Allows the filesystem to communicate to nfsd that it may want to do things + * differently when dealing with it. + * * Locking rules: * get_parent is called with child->d_inode->i_rwsem down * get_name is not (which is possibly inconsistent) -- cgit v1.2.3 From a39162f77f49b618df5a721a1e48d8b903280fbd Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Thu, 29 Jan 2026 11:02:11 +0100 Subject: 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: 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 --- include/linux/exportfs.h | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) (limited to 'include/linux/exportfs.h') diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h index 262e24d83313..0660953c3fb7 100644 --- a/include/linux/exportfs.h +++ b/include/linux/exportfs.h @@ -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. -- cgit v1.2.3 From b3c78bc53630d14a5770451ede3a30e7052f3b8b Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Thu, 29 Jan 2026 11:02:12 +0100 Subject: nfsd: do not allow exporting of special kernel filesystems 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 --- fs/nfsd/export.c | 8 +++++--- include/linux/exportfs.h | 9 +++++++++ 2 files changed, 14 insertions(+), 3 deletions(-) (limited to 'include/linux/exportfs.h') diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c index 9d55512d0cc9..baaa18b878d7 100644 --- a/fs/nfsd/export.c +++ b/fs/nfsd/export.c @@ -427,7 +427,8 @@ static int check_export(const struct path *path, int *flags, unsigned char *uuid * either a device number (so FS_REQUIRES_DEV needed) * or an FSID number (so NFSEXP_FSID or ->uuid is needed). * 2: We must be able to find an inode from a filehandle. - * This means that s_export_op must be set. + * This means that s_export_op must be set and comply with + * the requirements for remote filesystem export. * 3: We must not currently be on an idmapped mount. */ if (!(inode->i_sb->s_type->fs_flags & FS_REQUIRES_DEV) && @@ -437,8 +438,9 @@ static int check_export(const struct path *path, int *flags, unsigned char *uuid return -EINVAL; } - if (!exportfs_can_decode_fh(inode->i_sb->s_export_op)) { - dprintk("exp_export: export of invalid fs type.\n"); + if (!exportfs_may_export(inode->i_sb->s_export_op)) { + dprintk("exp_export: export of invalid fs type (%s).\n", + inode->i_sb->s_type->name); return -EINVAL; } diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h index 0660953c3fb7..8bcdba28b406 100644 --- a/include/linux/exportfs.h +++ b/include/linux/exportfs.h @@ -338,6 +338,15 @@ static inline bool exportfs_can_decode_fh(const struct export_operations *nop) return nop && nop->fh_to_dentry; } +static inline bool exportfs_may_export(const struct export_operations *nop) +{ + /* + * Do not allow nfs export for filesystems with custom ->open() or + * ->permission() ops, which nfsd does not respect (e.g. pidfs, nsfs). + */ + return exportfs_can_decode_fh(nop) && !nop->open && !nop->permission; +} + static inline bool exportfs_can_encode_fh(const struct export_operations *nop, int fh_flags) { -- cgit v1.2.3