// SPDX-License-Identifier: GPL-2.0-only

  /*
   * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.

   * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.

   */

  #include <linux/spinlock.h>
  #include <linux/completion.h>
  #include <linux/buffer_head.h>

  #include <linux/exportfs.h>

  #include <linux/gfs2_ondisk.h>

  #include <linux/crc32.h>

  
  #include "gfs2.h"

  #include "incore.h"

  #include "dir.h"
  #include "glock.h"
  #include "glops.h"
  #include "inode.h"

  #include "super.h"

  #include "rgrp.h"

  #include "util.h"

  #define GFS2_SMALL_FH_SIZE 4

  #define GFS2_LARGE_FH_SIZE 8

  #define GFS2_OLD_FH_SIZE 10

  static int gfs2_encode_fh(struct inode *inode, __u32 *p, int *len,
  			  struct inode *parent)

  {

  	__be32 *fh = (__force __be32 *)p;

  	struct super_block *sb = inode->i_sb;

  	struct gfs2_inode *ip = GFS2_I(inode);

  	if (parent && (*len < GFS2_LARGE_FH_SIZE)) {

  		*len = GFS2_LARGE_FH_SIZE;

  		return FILEID_INVALID;

  	} else if (*len < GFS2_SMALL_FH_SIZE) {
  		*len = GFS2_SMALL_FH_SIZE;

  		return FILEID_INVALID;

  	}

  	fh[0] = cpu_to_be32(ip->i_no_formal_ino >> 32);
  	fh[1] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
  	fh[2] = cpu_to_be32(ip->i_no_addr >> 32);
  	fh[3] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);

  	*len = GFS2_SMALL_FH_SIZE;

  	if (!parent || inode == d_inode(sb->s_root))

  		return *len;

  	ip = GFS2_I(parent);

  	fh[4] = cpu_to_be32(ip->i_no_formal_ino >> 32);
  	fh[5] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
  	fh[6] = cpu_to_be32(ip->i_no_addr >> 32);
  	fh[7] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);

  	*len = GFS2_LARGE_FH_SIZE;

  	return *len;
  }
  
  struct get_name_filldir {

  	struct dir_context ctx;

  	struct gfs2_inum_host inum;

  	char *name;
  };

  static int get_name_filldir(struct dir_context *ctx, const char *name,
  			    int length, loff_t offset, u64 inum,
  			    unsigned int type)

  {

  	struct get_name_filldir *gnfd =
  		container_of(ctx, struct get_name_filldir, ctx);

  	if (inum != gnfd->inum.no_addr)

  		return 0;
  
  	memcpy(gnfd->name, name, length);
  	gnfd->name[length] = 0;
  
  	return 1;
  }
  
  static int gfs2_get_name(struct dentry *parent, char *name,
  			 struct dentry *child)
  {

  	struct inode *dir = d_inode(parent);
  	struct inode *inode = d_inode(child);

  	struct gfs2_inode *dip, *ip;

  	struct get_name_filldir gnfd = {
  		.ctx.actor = get_name_filldir,
  		.name = name
  	};

  	struct gfs2_holder gh;

  	int error;

  	struct file_ra_state f_ra = { .start = 0 };

  
  	if (!dir)
  		return -EINVAL;

  	if (!S_ISDIR(dir->i_mode) || !inode)
  		return -EINVAL;

  	dip = GFS2_I(dir);
  	ip = GFS2_I(inode);

  
  	*name = 0;

  	gnfd.inum.no_addr = ip->i_no_addr;
  	gnfd.inum.no_formal_ino = ip->i_no_formal_ino;

  
  	error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED, 0, &gh);
  	if (error)
  		return error;

  	error = gfs2_dir_read(dir, &gnfd.ctx, &f_ra);

  
  	gfs2_glock_dq_uninit(&gh);
  
  	if (!error && !*name)
  		error = -ENOENT;
  
  	return error;
  }
  
  static struct dentry *gfs2_get_parent(struct dentry *child)
  {

  	return d_obtain_alias(gfs2_lookupi(d_inode(child), &gfs2_qdotdot, 1));

  }

  static struct dentry *gfs2_get_dentry(struct super_block *sb,

  				      struct gfs2_inum_host *inum)

  {

  	struct gfs2_sbd *sdp = sb->s_fs_info;

  	struct inode *inode;

  	if (!inum->no_formal_ino)
  		return ERR_PTR(-ESTALE);
  	inode = gfs2_lookup_by_inum(sdp, inum->no_addr, inum->no_formal_ino,

  				    GFS2_BLKST_DINODE);
  	if (IS_ERR(inode))
  		return ERR_CAST(inode);

  	return d_obtain_alias(inode);

  }

  static struct dentry *gfs2_fh_to_dentry(struct super_block *sb, struct fid *fid,
  		int fh_len, int fh_type)
  {
  	struct gfs2_inum_host this;
  	__be32 *fh = (__force __be32 *)fid->raw;
  
  	switch (fh_type) {
  	case GFS2_SMALL_FH_SIZE:
  	case GFS2_LARGE_FH_SIZE:
  	case GFS2_OLD_FH_SIZE:

  		if (fh_len < GFS2_SMALL_FH_SIZE)
  			return NULL;

  		this.no_formal_ino = ((u64)be32_to_cpu(fh[0])) << 32;
  		this.no_formal_ino |= be32_to_cpu(fh[1]);
  		this.no_addr = ((u64)be32_to_cpu(fh[2])) << 32;
  		this.no_addr |= be32_to_cpu(fh[3]);
  		return gfs2_get_dentry(sb, &this);
  	default:
  		return NULL;
  	}
  }
  
  static struct dentry *gfs2_fh_to_parent(struct super_block *sb, struct fid *fid,
  		int fh_len, int fh_type)
  {
  	struct gfs2_inum_host parent;
  	__be32 *fh = (__force __be32 *)fid->raw;
  
  	switch (fh_type) {
  	case GFS2_LARGE_FH_SIZE:
  	case GFS2_OLD_FH_SIZE:

  		if (fh_len < GFS2_LARGE_FH_SIZE)
  			return NULL;

  		parent.no_formal_ino = ((u64)be32_to_cpu(fh[4])) << 32;
  		parent.no_formal_ino |= be32_to_cpu(fh[5]);
  		parent.no_addr = ((u64)be32_to_cpu(fh[6])) << 32;
  		parent.no_addr |= be32_to_cpu(fh[7]);
  		return gfs2_get_dentry(sb, &parent);
  	default:
  		return NULL;
  	}
  }

  const struct export_operations gfs2_export_ops = {

  	.encode_fh = gfs2_encode_fh,

  	.fh_to_dentry = gfs2_fh_to_dentry,
  	.fh_to_parent = gfs2_fh_to_parent,

  	.get_name = gfs2_get_name,
  	.get_parent = gfs2_get_parent,

  };