fs/gfs2/export.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
   4  * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
   5  */
   6
   7 #include <linux/spinlock.h>
   8 #include <linux/completion.h>
   9 #include <linux/buffer_head.h>
  10 #include <linux/exportfs.h>
  11 #include <linux/gfs2_ondisk.h>
  12 #include <linux/crc32.h>
  13
  14 #include "gfs2.h"
  15 #include "incore.h"
  16 #include "dir.h"
  17 #include "glock.h"
  18 #include "glops.h"
  19 #include "inode.h"
  20 #include "super.h"
  21 #include "rgrp.h"
  22 #include "util.h"
  23
  24 #define GFS2_SMALL_FH_SIZE 4
  25 #define GFS2_LARGE_FH_SIZE 8
  26 #define GFS2_OLD_FH_SIZE 10
  27
  28 static int gfs2_encode_fh(struct inode *inode, __u32 *p, int *len,
  29                           struct inode *parent)
  30 {
  31         __be32 *fh = (__force __be32 *)p;
  32         struct super_block *sb = inode->i_sb;
  33         struct gfs2_inode *ip = GFS2_I(inode);
  34
  35         if (parent && (*len < GFS2_LARGE_FH_SIZE)) {
  36                 *len = GFS2_LARGE_FH_SIZE;
  37                 return FILEID_INVALID;
  38         } else if (*len < GFS2_SMALL_FH_SIZE) {
  39                 *len = GFS2_SMALL_FH_SIZE;
  40                 return FILEID_INVALID;
  41         }
  42
  43         fh[0] = cpu_to_be32(ip->i_no_formal_ino >> 32);
  44         fh[1] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
  45         fh[2] = cpu_to_be32(ip->i_no_addr >> 32);
  46         fh[3] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
  47         *len = GFS2_SMALL_FH_SIZE;
  48
  49         if (!parent || inode == d_inode(sb->s_root))
  50                 return *len;
  51
  52         ip = GFS2_I(parent);
  53
  54         fh[4] = cpu_to_be32(ip->i_no_formal_ino >> 32);
  55         fh[5] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
  56         fh[6] = cpu_to_be32(ip->i_no_addr >> 32);
  57         fh[7] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
  58         *len = GFS2_LARGE_FH_SIZE;
  59
  60         return *len;
  61 }
  62
  63 struct get_name_filldir {
  64         struct dir_context ctx;
  65         struct gfs2_inum_host inum;
  66         char *name;
  67 };
  68
  69 static bool get_name_filldir(struct dir_context *ctx, const char *name,
  70                             int length, loff_t offset, u64 inum,
  71                             unsigned int type)
  72 {
  73         struct get_name_filldir *gnfd =
  74                 container_of(ctx, struct get_name_filldir, ctx);
  75
  76         if (inum != gnfd->inum.no_addr)
  77                 return true;
  78
  79         memcpy(gnfd->name, name, length);
  80         gnfd->name[length] = 0;
  81
  82         return false;
  83 }
  84
  85 static int gfs2_get_name(struct dentry *parent, char *name,
  86                          struct dentry *child)
  87 {
  88         struct inode *dir = d_inode(parent);
  89         struct inode *inode = d_inode(child);
  90         struct gfs2_inode *dip, *ip;
  91         struct get_name_filldir gnfd = {
  92                 .ctx.actor = get_name_filldir,
  93                 .name = name
  94         };
  95         struct gfs2_holder gh;
  96         int error;
  97         struct file_ra_state f_ra = { .start = 0 };
  98
  99         if (!dir)
 100                 return -EINVAL;
 101
 102         if (!S_ISDIR(dir->i_mode) || !inode)
 103                 return -EINVAL;
 104
 105         dip = GFS2_I(dir);
 106         ip = GFS2_I(inode);
 107
 108         *name = 0;
 109         gnfd.inum.no_addr = ip->i_no_addr;
 110         gnfd.inum.no_formal_ino = ip->i_no_formal_ino;
 111
 112         error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED, 0, &gh);
 113         if (error)
 114                 return error;
 115
 116         error = gfs2_dir_read(dir, &gnfd.ctx, &f_ra);
 117
 118         gfs2_glock_dq_uninit(&gh);
 119
 120         if (!error && !*name)
 121                 error = -ENOENT;
 122
 123         return error;
 124 }
 125
 126 static struct dentry *gfs2_get_parent(struct dentry *child)
 127 {
 128         return d_obtain_alias(gfs2_lookupi(d_inode(child), &gfs2_qdotdot, 1));
 129 }
 130
 131 static struct dentry *gfs2_get_dentry(struct super_block *sb,
 132                                       struct gfs2_inum_host *inum)
 133 {
 134         struct gfs2_sbd *sdp = sb->s_fs_info;
 135         struct inode *inode;
 136
 137         if (!inum->no_formal_ino)
 138                 return ERR_PTR(-ESTALE);
 139         inode = gfs2_lookup_by_inum(sdp, inum->no_addr, inum->no_formal_ino,
 140                                     GFS2_BLKST_DINODE);
 141         if (IS_ERR(inode))
 142                 return ERR_CAST(inode);
 143         return d_obtain_alias(inode);
 144 }
 145
 146 static struct dentry *gfs2_fh_to_dentry(struct super_block *sb, struct fid *fid,
 147                 int fh_len, int fh_type)
 148 {
 149         struct gfs2_inum_host this;
 150         __be32 *fh = (__force __be32 *)fid->raw;
 151
 152         switch (fh_type) {
 153         case GFS2_SMALL_FH_SIZE:
 154         case GFS2_LARGE_FH_SIZE:
 155         case GFS2_OLD_FH_SIZE:
 156                 if (fh_len < GFS2_SMALL_FH_SIZE)
 157                         return NULL;
 158                 this.no_formal_ino = ((u64)be32_to_cpu(fh[0])) << 32;
 159                 this.no_formal_ino |= be32_to_cpu(fh[1]);
 160                 this.no_addr = ((u64)be32_to_cpu(fh[2])) << 32;
 161                 this.no_addr |= be32_to_cpu(fh[3]);
 162                 return gfs2_get_dentry(sb, &this);
 163         default:
 164                 return NULL;
 165         }
 166 }
 167
 168 static struct dentry *gfs2_fh_to_parent(struct super_block *sb, struct fid *fid,
 169                 int fh_len, int fh_type)
 170 {
 171         struct gfs2_inum_host parent;
 172         __be32 *fh = (__force __be32 *)fid->raw;
 173
 174         switch (fh_type) {
 175         case GFS2_LARGE_FH_SIZE:
 176         case GFS2_OLD_FH_SIZE:
 177                 if (fh_len < GFS2_LARGE_FH_SIZE)
 178                         return NULL;
 179                 parent.no_formal_ino = ((u64)be32_to_cpu(fh[4])) << 32;
 180                 parent.no_formal_ino |= be32_to_cpu(fh[5]);
 181                 parent.no_addr = ((u64)be32_to_cpu(fh[6])) << 32;
 182                 parent.no_addr |= be32_to_cpu(fh[7]);
 183                 return gfs2_get_dentry(sb, &parent);
 184         default:
 185                 return NULL;
 186         }
 187 }
 188
 189 const struct export_operations gfs2_export_ops = {
 190         .encode_fh = gfs2_encode_fh,
 191         .fh_to_dentry = gfs2_fh_to_dentry,
 192         .fh_to_parent = gfs2_fh_to_parent,
 193         .get_name = gfs2_get_name,
 194         .get_parent = gfs2_get_parent,
 195 };
 196