linux/fs/orangefs/dir.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright 2017 Omnibond Systems, L.L.C.
 */

#include "protocol.h"
#include "orangefs-kernel.h"
#include "orangefs-bufmap.h"

struct orangefs_dir_part { … };

struct orangefs_dir { … };

#define PART_SHIFT …
#define PART_SIZE …
#define PART_MASK …

/*
 * There can be up to 512 directory entries.  Each entry is encoded as
 * follows:
 * 4 bytes: string size (n)
 * n bytes: string
 * 1 byte: trailing zero
 * padding to 8 bytes
 * 16 bytes: khandle
 * padding to 8 bytes
 *
 * The trailer_buf starts with a struct orangefs_readdir_response_s
 * which must be skipped to get to the directory data.
 *
 * The data which is received from the userspace daemon is termed a
 * part and is stored in a linked list in case more than one part is
 * needed for a large directory.
 *
 * The position pointer (ctx->pos) encodes the part and offset on which
 * to begin reading at.  Bits above PART_SHIFT encode the part and bits
 * below PART_SHIFT encode the offset.  Parts are stored in a linked
 * list which grows as data is received from the server.  The overhead
 * associated with managing the list is presumed to be small compared to
 * the overhead of communicating with the server.
 *
 * As data is received from the server, it is placed at the end of the
 * part list.  Data is parsed from the current position as it is needed.
 * When data is determined to be corrupt, it is either because the
 * userspace component has sent back corrupt data or because the file
 * pointer has been moved to an invalid location.  Since the two cannot
 * be differentiated, return EIO.
 *
 * Part zero is synthesized to contains `.' and `..'.  Part one is the
 * first part of the part list.
 */

static int do_readdir(struct orangefs_dir *od, struct inode *inode,
    struct orangefs_kernel_op_s *op)
{ … }

static int parse_readdir(struct orangefs_dir *od,
    struct orangefs_kernel_op_s *op)
{ … }

static int orangefs_dir_more(struct orangefs_dir *od, struct inode *inode)
{ … }

static int fill_from_part(struct orangefs_dir_part *part,
    struct dir_context *ctx)
{ … }

static int orangefs_dir_fill(struct orangefs_dir *od, struct dir_context *ctx)
{ … }

static loff_t orangefs_dir_llseek(struct file *file, loff_t offset,
    int whence)
{ … }

static int orangefs_dir_iterate(struct file *file,
    struct dir_context *ctx)
{ … }

static int orangefs_dir_open(struct inode *inode, struct file *file)
{ … }

static int orangefs_dir_release(struct inode *inode, struct file *file)
{ … }

const struct file_operations orangefs_dir_operations = …;