fs/gfs2/ops_export.c

   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/slab.h>
  11 #include <linux/spinlock.h>
  12 #include <linux/completion.h>
  13 #include <linux/buffer_head.h>
  14 #include <linux/exportfs.h>
  15 #include <linux/gfs2_ondisk.h>
  16 #include <linux/crc32.h>
  17 #include <linux/lm_interface.h>
  18
  19 #include "gfs2.h"
  20 #include "incore.h"
  21 #include "dir.h"
  22 #include "glock.h"
  23 #include "glops.h"
  24 #include "inode.h"
  25 #include "ops_dentry.h"
  26 #include "ops_fstype.h"
  27 #include "rgrp.h"
  28 #include "util.h"
  29
  30 #define GFS2_SMALL_FH_SIZE 4
  31 #define GFS2_LARGE_FH_SIZE 8
  32 #define GFS2_OLD_FH_SIZE 10
  33
  34 static struct dentry *gfs2_decode_fh(struct super_block *sb,
  35                                      __u32 *p,
  36                                      int fh_len,
  37                                      int fh_type,
  38                                      int (*acceptable)(void *context,
  39                                                        struct dentry *dentry),
  40                                      void *context)
  41 {
  42         __be32 *fh = (__force __be32 *)p;
  43         struct gfs2_inum_host inum, parent;
  44
  45         memset(&parent, 0, sizeof(struct gfs2_inum));
  46
  47         switch (fh_len) {
  48         case GFS2_LARGE_FH_SIZE:
  49         case GFS2_OLD_FH_SIZE:
  50                 parent.no_formal_ino = ((u64)be32_to_cpu(fh[4])) << 32;
  51                 parent.no_formal_ino |= be32_to_cpu(fh[5]);
  52                 parent.no_addr = ((u64)be32_to_cpu(fh[6])) << 32;
  53                 parent.no_addr |= be32_to_cpu(fh[7]);
  54         case GFS2_SMALL_FH_SIZE:
  55                 inum.no_formal_ino = ((u64)be32_to_cpu(fh[0])) << 32;
  56                 inum.no_formal_ino |= be32_to_cpu(fh[1]);
  57                 inum.no_addr = ((u64)be32_to_cpu(fh[2])) << 32;
  58                 inum.no_addr |= be32_to_cpu(fh[3]);
  59                 break;
  60         default:
  61                 return NULL;
  62         }
  63
  64         return gfs2_export_ops.find_exported_dentry(sb, &inum, &parent,
  65                                                     acceptable, context);
  66 }
  67
  68 static int gfs2_encode_fh(struct dentry *dentry, __u32 *p, int *len,
  69                           int connectable)
  70 {
  71         __be32 *fh = (__force __be32 *)p;
  72         struct inode *inode = dentry->d_inode;
  73         struct super_block *sb = inode->i_sb;
  74         struct gfs2_inode *ip = GFS2_I(inode);
  75
  76         if (*len < GFS2_SMALL_FH_SIZE ||
  77             (connectable && *len < GFS2_LARGE_FH_SIZE))
  78                 return 255;
  79
  80         fh[0] = cpu_to_be32(ip->i_no_formal_ino >> 32);
  81         fh[1] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
  82         fh[2] = cpu_to_be32(ip->i_no_addr >> 32);
  83         fh[3] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
  84         *len = GFS2_SMALL_FH_SIZE;
  85
  86         if (!connectable || inode == sb->s_root->d_inode)
  87                 return *len;
  88
  89         spin_lock(&dentry->d_lock);
  90         inode = dentry->d_parent->d_inode;
  91         ip = GFS2_I(inode);
  92         igrab(inode);
  93         spin_unlock(&dentry->d_lock);
  94
  95         fh[4] = cpu_to_be32(ip->i_no_formal_ino >> 32);
  96         fh[5] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
  97         fh[6] = cpu_to_be32(ip->i_no_addr >> 32);
  98         fh[7] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
  99         *len = GFS2_LARGE_FH_SIZE;
 100
 101         iput(inode);
 102
 103         return *len;
 104 }
 105
 106 struct get_name_filldir {
 107         struct gfs2_inum_host inum;
 108         char *name;
 109 };
 110
 111 static int get_name_filldir(void *opaque, const char *name, int length,
 112                             loff_t offset, u64 inum, unsigned int type)
 113 {
 114         struct get_name_filldir *gnfd = opaque;
 115
 116         if (inum != gnfd->inum.no_addr)
 117                 return 0;
 118
 119         memcpy(gnfd->name, name, length);
 120         gnfd->name[length] = 0;
 121
 122         return 1;
 123 }
 124
 125 static int gfs2_get_name(struct dentry *parent, char *name,
 126                          struct dentry *child)
 127 {
 128         struct inode *dir = parent->d_inode;
 129         struct inode *inode = child->d_inode;
 130         struct gfs2_inode *dip, *ip;
 131         struct get_name_filldir gnfd;
 132         struct gfs2_holder gh;
 133         u64 offset = 0;
 134         int error;
 135
 136         if (!dir)
 137                 return -EINVAL;
 138
 139         if (!S_ISDIR(dir->i_mode) || !inode)
 140                 return -EINVAL;
 141
 142         dip = GFS2_I(dir);
 143         ip = GFS2_I(inode);
 144
 145         *name = 0;
 146         gnfd.inum.no_addr = ip->i_no_addr;
 147         gnfd.inum.no_formal_ino = ip->i_no_formal_ino;
 148         gnfd.name = name;
 149
 150         error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED, 0, &gh);
 151         if (error)
 152                 return error;
 153
 154         error = gfs2_dir_read(dir, &offset, &gnfd, get_name_filldir);
 155
 156         gfs2_glock_dq_uninit(&gh);
 157
 158         if (!error && !*name)
 159                 error = -ENOENT;
 160
 161         return error;
 162 }
 163
 164 static struct dentry *gfs2_get_parent(struct dentry *child)
 165 {
 166         struct qstr dotdot;
 167         struct inode *inode;
 168         struct dentry *dentry;
 169
 170         gfs2_str2qstr(&dotdot, "..");
 171         inode = gfs2_lookupi(child->d_inode, &dotdot, 1, NULL);
 172
 173         if (!inode)
 174                 return ERR_PTR(-ENOENT);
 175         /*
 176          * In case of an error, @inode carries the error value, and we
 177          * have to return that as a(n invalid) pointer to dentry.
 178          */
 179         if (IS_ERR(inode))
 180                 return ERR_PTR(PTR_ERR(inode));
 181
 182         dentry = d_alloc_anon(inode);
 183         if (!dentry) {
 184                 iput(inode);
 185                 return ERR_PTR(-ENOMEM);
 186         }
 187
 188         dentry->d_op = &gfs2_dops;
 189         return dentry;
 190 }
 191
 192 static struct dentry *gfs2_get_dentry(struct super_block *sb, void *inum_obj)
 193 {
 194         struct gfs2_sbd *sdp = sb->s_fs_info;
 195         struct gfs2_inum_host *inum = inum_obj;
 196         struct gfs2_holder i_gh, ri_gh, rgd_gh;
 197         struct gfs2_rgrpd *rgd;
 198         struct inode *inode;
 199         struct dentry *dentry;
 200         int error;
 201
 202         /* System files? */
 203
 204         inode = gfs2_ilookup(sb, inum->no_addr);
 205         if (inode) {
 206                 if (GFS2_I(inode)->i_no_formal_ino != inum->no_formal_ino) {
 207                         iput(inode);
 208                         return ERR_PTR(-ESTALE);
 209                 }
 210                 goto out_inode;
 211         }
 212
 213         error = gfs2_glock_nq_num(sdp, inum->no_addr, &gfs2_inode_glops,
 214                                   LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
 215         if (error)
 216                 return ERR_PTR(error);
 217
 218         error = gfs2_rindex_hold(sdp, &ri_gh);
 219         if (error)
 220                 goto fail;
 221
 222         error = -EINVAL;
 223         rgd = gfs2_blk2rgrpd(sdp, inum->no_addr);
 224         if (!rgd)
 225                 goto fail_rindex;
 226
 227         error = gfs2_glock_nq_init(rgd->rd_gl, LM_ST_SHARED, 0, &rgd_gh);
 228         if (error)
 229                 goto fail_rindex;
 230
 231         error = -ESTALE;
 232         if (gfs2_get_block_type(rgd, inum->no_addr) != GFS2_BLKST_DINODE)
 233                 goto fail_rgd;
 234
 235         gfs2_glock_dq_uninit(&rgd_gh);
 236         gfs2_glock_dq_uninit(&ri_gh);
 237
 238         inode = gfs2_inode_lookup(sb, DT_UNKNOWN,
 239                                         inum->no_addr,
 240                                         0, 0);
 241         if (!inode)
 242                 goto fail;
 243         if (IS_ERR(inode)) {
 244                 error = PTR_ERR(inode);
 245                 goto fail;
 246         }
 247
 248         error = gfs2_inode_refresh(GFS2_I(inode));
 249         if (error) {
 250                 iput(inode);
 251                 goto fail;
 252         }
 253
 254         /* Pick up the works we bypass in gfs2_inode_lookup */
 255         if (inode->i_state & I_NEW)
 256                 gfs2_set_iop(inode);
 257
 258         if (GFS2_I(inode)->i_no_formal_ino != inum->no_formal_ino) {
 259                 iput(inode);
 260                 goto fail;
 261         }
 262
 263         error = -EIO;
 264         if (GFS2_I(inode)->i_di.di_flags & GFS2_DIF_SYSTEM) {
 265                 iput(inode);
 266                 goto fail;
 267         }
 268
 269         gfs2_glock_dq_uninit(&i_gh);
 270
 271 out_inode:
 272         dentry = d_alloc_anon(inode);
 273         if (!dentry) {
 274                 iput(inode);
 275                 return ERR_PTR(-ENOMEM);
 276         }
 277
 278         dentry->d_op = &gfs2_dops;
 279         return dentry;
 280
 281 fail_rgd:
 282         gfs2_glock_dq_uninit(&rgd_gh);
 283
 284 fail_rindex:
 285         gfs2_glock_dq_uninit(&ri_gh);
 286
 287 fail:
 288         gfs2_glock_dq_uninit(&i_gh);
 289         return ERR_PTR(error);
 290 }
 291
 292 struct export_operations gfs2_export_ops = {
 293         .decode_fh = gfs2_decode_fh,
 294         .encode_fh = gfs2_encode_fh,
 295         .get_name = gfs2_get_name,
 296         .get_parent = gfs2_get_parent,
 297         .get_dentry = gfs2_get_dentry,
 298 };
 299