linux/fs/gfs2/export.c
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   1/*
   2 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
   3 * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
   4 *
   5 * This copyrighted material is made available to anyone wishing to use,
   6 * modify, copy, or redistribute it subject to the terms and conditions
   7 * of the GNU General Public License version 2.
   8 */
   9
  10#include <linux/spinlock.h>
  11#include <linux/completion.h>
  12#include <linux/buffer_head.h>
  13#include <linux/exportfs.h>
  14#include <linux/gfs2_ondisk.h>
  15#include <linux/crc32.h>
  16
  17#include "gfs2.h"
  18#include "incore.h"
  19#include "dir.h"
  20#include "glock.h"
  21#include "glops.h"
  22#include "inode.h"
  23#include "super.h"
  24#include "rgrp.h"
  25#include "util.h"
  26
  27#define GFS2_SMALL_FH_SIZE 4
  28#define GFS2_LARGE_FH_SIZE 8
  29#define GFS2_OLD_FH_SIZE 10
  30
  31static int gfs2_encode_fh(struct inode *inode, __u32 *p, int *len,
  32                          struct inode *parent)
  33{
  34        __be32 *fh = (__force __be32 *)p;
  35        struct super_block *sb = inode->i_sb;
  36        struct gfs2_inode *ip = GFS2_I(inode);
  37
  38        if (parent && (*len < GFS2_LARGE_FH_SIZE)) {
  39                *len = GFS2_LARGE_FH_SIZE;
  40                return 255;
  41        } else if (*len < GFS2_SMALL_FH_SIZE) {
  42                *len = GFS2_SMALL_FH_SIZE;
  43                return 255;
  44        }
  45
  46        fh[0] = cpu_to_be32(ip->i_no_formal_ino >> 32);
  47        fh[1] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
  48        fh[2] = cpu_to_be32(ip->i_no_addr >> 32);
  49        fh[3] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
  50        *len = GFS2_SMALL_FH_SIZE;
  51
  52        if (!parent || inode == sb->s_root->d_inode)
  53                return *len;
  54
  55        ip = GFS2_I(parent);
  56
  57        fh[4] = cpu_to_be32(ip->i_no_formal_ino >> 32);
  58        fh[5] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
  59        fh[6] = cpu_to_be32(ip->i_no_addr >> 32);
  60        fh[7] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
  61        *len = GFS2_LARGE_FH_SIZE;
  62
  63        return *len;
  64}
  65
  66struct get_name_filldir {
  67        struct gfs2_inum_host inum;
  68        char *name;
  69};
  70
  71static int get_name_filldir(void *opaque, const char *name, int length,
  72                            loff_t offset, u64 inum, unsigned int type)
  73{
  74        struct get_name_filldir *gnfd = opaque;
  75
  76        if (inum != gnfd->inum.no_addr)
  77                return 0;
  78
  79        memcpy(gnfd->name, name, length);
  80        gnfd->name[length] = 0;
  81
  82        return 1;
  83}
  84
  85static int gfs2_get_name(struct dentry *parent, char *name,
  86                         struct dentry *child)
  87{
  88        struct inode *dir = parent->d_inode;
  89        struct inode *inode = child->d_inode;
  90        struct gfs2_inode *dip, *ip;
  91        struct get_name_filldir gnfd;
  92        struct gfs2_holder gh;
  93        u64 offset = 0;
  94        int error;
  95        struct file_ra_state f_ra = { .start = 0 };
  96
  97        if (!dir)
  98                return -EINVAL;
  99
 100        if (!S_ISDIR(dir->i_mode) || !inode)
 101                return -EINVAL;
 102
 103        dip = GFS2_I(dir);
 104        ip = GFS2_I(inode);
 105
 106        *name = 0;
 107        gnfd.inum.no_addr = ip->i_no_addr;
 108        gnfd.inum.no_formal_ino = ip->i_no_formal_ino;
 109        gnfd.name = name;
 110
 111        error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED, 0, &gh);
 112        if (error)
 113                return error;
 114
 115        error = gfs2_dir_read(dir, &offset, &gnfd, get_name_filldir, &f_ra);
 116
 117        gfs2_glock_dq_uninit(&gh);
 118
 119        if (!error && !*name)
 120                error = -ENOENT;
 121
 122        return error;
 123}
 124
 125static struct dentry *gfs2_get_parent(struct dentry *child)
 126{
 127        return d_obtain_alias(gfs2_lookupi(child->d_inode, &gfs2_qdotdot, 1));
 128}
 129
 130static struct dentry *gfs2_get_dentry(struct super_block *sb,
 131                                      struct gfs2_inum_host *inum)
 132{
 133        struct gfs2_sbd *sdp = sb->s_fs_info;
 134        struct inode *inode;
 135
 136        inode = gfs2_ilookup(sb, inum->no_addr, 0);
 137        if (inode) {
 138                if (GFS2_I(inode)->i_no_formal_ino != inum->no_formal_ino) {
 139                        iput(inode);
 140                        return ERR_PTR(-ESTALE);
 141                }
 142                goto out_inode;
 143        }
 144
 145        inode = gfs2_lookup_by_inum(sdp, inum->no_addr, &inum->no_formal_ino,
 146                                    GFS2_BLKST_DINODE);
 147        if (IS_ERR(inode))
 148                return ERR_CAST(inode);
 149
 150out_inode:
 151        return d_obtain_alias(inode);
 152}
 153
 154static struct dentry *gfs2_fh_to_dentry(struct super_block *sb, struct fid *fid,
 155                int fh_len, int fh_type)
 156{
 157        struct gfs2_inum_host this;
 158        __be32 *fh = (__force __be32 *)fid->raw;
 159
 160        switch (fh_type) {
 161        case GFS2_SMALL_FH_SIZE:
 162        case GFS2_LARGE_FH_SIZE:
 163        case GFS2_OLD_FH_SIZE:
 164                this.no_formal_ino = ((u64)be32_to_cpu(fh[0])) << 32;
 165                this.no_formal_ino |= be32_to_cpu(fh[1]);
 166                this.no_addr = ((u64)be32_to_cpu(fh[2])) << 32;
 167                this.no_addr |= be32_to_cpu(fh[3]);
 168                return gfs2_get_dentry(sb, &this);
 169        default:
 170                return NULL;
 171        }
 172}
 173
 174static struct dentry *gfs2_fh_to_parent(struct super_block *sb, struct fid *fid,
 175                int fh_len, int fh_type)
 176{
 177        struct gfs2_inum_host parent;
 178        __be32 *fh = (__force __be32 *)fid->raw;
 179
 180        switch (fh_type) {
 181        case GFS2_LARGE_FH_SIZE:
 182        case GFS2_OLD_FH_SIZE:
 183                parent.no_formal_ino = ((u64)be32_to_cpu(fh[4])) << 32;
 184                parent.no_formal_ino |= be32_to_cpu(fh[5]);
 185                parent.no_addr = ((u64)be32_to_cpu(fh[6])) << 32;
 186                parent.no_addr |= be32_to_cpu(fh[7]);
 187                return gfs2_get_dentry(sb, &parent);
 188        default:
 189                return NULL;
 190        }
 191}
 192
 193const struct export_operations gfs2_export_ops = {
 194        .encode_fh = gfs2_encode_fh,
 195        .fh_to_dentry = gfs2_fh_to_dentry,
 196        .fh_to_parent = gfs2_fh_to_parent,
 197        .get_name = gfs2_get_name,
 198        .get_parent = gfs2_get_parent,
 199};
 200
 201
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