/* SPDX-License-Identifier: GPL-2.0 */ #ifndef LINUX_EXPORTFS_H #define LINUX_EXPORTFS_H … #include <linux/types.h> struct dentry; struct iattr; struct inode; struct iomap; struct super_block; struct vfsmount; /* limit the handle size to NFSv4 handle size now */ #define MAX_HANDLE_SZ … /* * The fileid_type identifies how the file within the filesystem is encoded. * In theory this is freely set and parsed by the filesystem, but we try to * stick to conventions so we can share some generic code and don't confuse * sniffers like ethereal/wireshark. * * The filesystem must not use the value '0' or '0xff'. */ enum fid_type { … }; struct fid { … }; #define EXPORT_FH_CONNECTABLE … #define EXPORT_FH_FID … #define EXPORT_FH_DIR_ONLY … /** * struct export_operations - for nfsd to communicate with file systems * @encode_fh: encode a file handle fragment from a dentry * @fh_to_dentry: find the implied object and get a dentry for it * @fh_to_parent: find the implied object's parent and get a dentry for it * @get_name: find the name for a given inode in a given directory * @get_parent: find the parent of a given directory * @commit_metadata: commit metadata changes to stable storage * * See Documentation/filesystems/nfs/exporting.rst for details on how to use * this interface correctly. * * 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 * set, the encode_fh() should store sufficient information so that a good * attempt can be made to find not only the file but also it's place in the * filesystem. This typically means storing a reference to de->d_parent in * the filehandle fragment. encode_fh() should return the fileid_type on * success and on error returns 255 (if the space needed to encode fh is * 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 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, * it should return a %NULL pointer if the file cannot be found, or an * %ERR_PTR error code of %ENOMEM if a memory allocation failure occurred. * Any other error code is treated like %NULL, and will cause an %ESTALE error * for callers of exportfs_decode_fh(). * Any suitable dentry can be returned including, if necessary, a new dentry * created with d_alloc_root. The caller can then find any other extant * dentries by following the d_alias links. * * 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 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_mutex held. * * 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. * * commit_metadata: * @commit_metadata should commit metadata changes to stable storage. * * Locking rules: * get_parent is called with child->d_inode->i_mutex down * get_name is not (which is possibly inconsistent) */ struct export_operations { … }; /** * exportfs_lock_op_is_async() - export op supports async lock operation * @export_ops: the nfs export operations to check * * Returns true if the nfs export_operations structure has * EXPORT_OP_ASYNC_LOCK in their flags set */ static inline bool exportfs_lock_op_is_async(const struct export_operations *export_ops) { … } extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid, int *max_len, struct inode *parent, int flags); extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid, int *max_len, int flags); static inline bool exportfs_can_encode_fid(const struct export_operations *nop) { … } static inline bool exportfs_can_decode_fh(const struct export_operations *nop) { … } static inline bool exportfs_can_encode_fh(const struct export_operations *nop, int fh_flags) { … } static inline int exportfs_encode_fid(struct inode *inode, struct fid *fid, int *max_len) { … } extern struct dentry *exportfs_decode_fh_raw(struct vfsmount *mnt, struct fid *fid, int fh_len, int fileid_type, unsigned int flags, int (*acceptable)(void *, struct dentry *), void *context); extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid, int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *), void *context); /* * Generic helpers for filesystems. */ int generic_encode_ino32_fh(struct inode *inode, __u32 *fh, int *max_len, struct inode *parent); struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid, int fh_len, int fh_type, struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen)); struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid, int fh_len, int fh_type, struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen)); #endif /* LINUX_EXPORTFS_H */
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