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/gfs2_ondisk.h>
  15 #include <linux/crc32.h>
  16 #include <linux/lm_interface.h>
  17
  18 #include "gfs2.h"
  19 #include "incore.h"
  20 #include "dir.h"
  21 #include "glock.h"
  22 #include "glops.h"
  23 #include "inode.h"
  24 #include "ops_dentry.h"
  25 #include "ops_export.h"
  26 #include "rgrp.h"
  27 #include "util.h"
  28
  29 static struct dentry *gfs2_decode_fh(struct super_block *sb,
  30                                      __u32 *p,
  31                                      int fh_len,
  32                                      int fh_type,
  33                                      int (*acceptable)(void *context,
  34                                                        struct dentry *dentry),
  35                                      void *context)
  36 {
  37         __be32 *fh = (__force __be32 *)p;
  38         struct gfs2_fh_obj fh_obj;
  39         struct gfs2_inum_host *this, parent;
  40
  41         this            = &fh_obj.this;
  42         fh_obj.imode    = DT_UNKNOWN;
  43         memset(&parent, 0, sizeof(struct gfs2_inum));
  44
  45         switch (fh_len) {
  46         case GFS2_LARGE_FH_SIZE:
  47                 parent.no_formal_ino = ((u64)be32_to_cpu(fh[4])) << 32;
  48                 parent.no_formal_ino |= be32_to_cpu(fh[5]);
  49                 parent.no_addr = ((u64)be32_to_cpu(fh[6])) << 32;
  50                 parent.no_addr |= be32_to_cpu(fh[7]);
  51                 fh_obj.imode = be32_to_cpu(fh[8]);
  52         case GFS2_SMALL_FH_SIZE:
  53                 this->no_formal_ino = ((u64)be32_to_cpu(fh[0])) << 32;
  54                 this->no_formal_ino |= be32_to_cpu(fh[1]);
  55                 this->no_addr = ((u64)be32_to_cpu(fh[2])) << 32;
  56                 this->no_addr |= be32_to_cpu(fh[3]);
  57                 break;
  58         default:
  59                 return NULL;
  60         }
  61
  62         return gfs2_export_ops.find_exported_dentry(sb, &fh_obj, &parent,
  63                                                     acceptable, context);
  64 }
  65
  66 static int gfs2_encode_fh(struct dentry *dentry, __u32 *p, int *len,
  67                           int connectable)
  68 {
  69         __be32 *fh = (__force __be32 *)p;
  70         struct inode *inode = dentry->d_inode;
  71         struct super_block *sb = inode->i_sb;
  72         struct gfs2_inode *ip = GFS2_I(inode);
  73
  74         if (*len < GFS2_SMALL_FH_SIZE ||
  75             (connectable && *len < GFS2_LARGE_FH_SIZE))
  76                 return 255;
  77
  78         fh[0] = cpu_to_be32(ip->i_num.no_formal_ino >> 32);
  79         fh[1] = cpu_to_be32(ip->i_num.no_formal_ino & 0xFFFFFFFF);
  80         fh[2] = cpu_to_be32(ip->i_num.no_addr >> 32);
  81         fh[3] = cpu_to_be32(ip->i_num.no_addr & 0xFFFFFFFF);
  82         *len = GFS2_SMALL_FH_SIZE;
  83
  84         if (!connectable || inode == sb->s_root->d_inode)
  85                 return *len;
  86
  87         spin_lock(&dentry->d_lock);
  88         inode = dentry->d_parent->d_inode;
  89         ip = GFS2_I(inode);
  90         igrab(inode);
  91         spin_unlock(&dentry->d_lock);
  92
  93         fh[4] = cpu_to_be32(ip->i_num.no_formal_ino >> 32);
  94         fh[5] = cpu_to_be32(ip->i_num.no_formal_ino & 0xFFFFFFFF);
  95         fh[6] = cpu_to_be32(ip->i_num.no_addr >> 32);
  96         fh[7] = cpu_to_be32(ip->i_num.no_addr & 0xFFFFFFFF);
  97
  98         fh[8]  = cpu_to_be32(inode->i_mode);
  99         fh[9]  = 0;     /* pad to double word */
 100         *len = GFS2_LARGE_FH_SIZE;
 101
 102         iput(inode);
 103
 104         return *len;
 105 }
 106
 107 struct get_name_filldir {
 108         struct gfs2_inum_host inum;
 109         char *name;
 110 };
 111
 112 static int get_name_filldir(void *opaque, const char *name, int length,
 113                             loff_t offset, u64 inum, unsigned int type)
 114 {
 115         struct get_name_filldir *gnfd = opaque;
 116
 117         if (inum != gnfd->inum.no_addr)
 118                 return 0;
 119
 120         memcpy(gnfd->name, name, length);
 121         gnfd->name[length] = 0;
 122
 123         return 1;
 124 }
 125
 126 static int gfs2_get_name(struct dentry *parent, char *name,
 127                          struct dentry *child)
 128 {
 129         struct inode *dir = parent->d_inode;
 130         struct inode *inode = child->d_inode;
 131         struct gfs2_inode *dip, *ip;
 132         struct get_name_filldir gnfd;
 133         struct gfs2_holder gh;
 134         u64 offset = 0;
 135         int error;
 136
 137         if (!dir)
 138                 return -EINVAL;
 139
 140         if (!S_ISDIR(dir->i_mode) || !inode)
 141                 return -EINVAL;
 142
 143         dip = GFS2_I(dir);
 144         ip = GFS2_I(inode);
 145
 146         *name = 0;
 147         gnfd.inum = ip->i_num;
 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_fh_obj *fh_obj = (struct gfs2_fh_obj *)inum_obj;
 196         struct gfs2_inum_host *inum = &fh_obj->this;
 197         struct gfs2_holder i_gh, ri_gh, rgd_gh;
 198         struct gfs2_rgrpd *rgd;
 199         struct inode *inode;
 200         struct dentry *dentry;
 201         int error;
 202
 203         /* System files? */
 204
 205         inode = gfs2_ilookup(sb, inum);
 206         if (inode) {
 207                 if (GFS2_I(inode)->i_num.no_formal_ino != inum->no_formal_ino) {
 208                         iput(inode);
 209                         return ERR_PTR(-ESTALE);
 210                 }
 211                 goto out_inode;
 212         }
 213
 214         error = gfs2_glock_nq_num(sdp, inum->no_addr, &gfs2_inode_glops,
 215                                   LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
 216         if (error)
 217                 return ERR_PTR(error);
 218
 219         error = gfs2_rindex_hold(sdp, &ri_gh);
 220         if (error)
 221                 goto fail;
 222
 223         error = -EINVAL;
 224         rgd = gfs2_blk2rgrpd(sdp, inum->no_addr);
 225         if (!rgd)
 226                 goto fail_rindex;
 227
 228         error = gfs2_glock_nq_init(rgd->rd_gl, LM_ST_SHARED, 0, &rgd_gh);
 229         if (error)
 230                 goto fail_rindex;
 231
 232         error = -ESTALE;
 233         if (gfs2_get_block_type(rgd, inum->no_addr) != GFS2_BLKST_DINODE)
 234                 goto fail_rgd;
 235
 236         gfs2_glock_dq_uninit(&rgd_gh);
 237         gfs2_glock_dq_uninit(&ri_gh);
 238
 239         inode = gfs2_inode_lookup(sb, inum, fh_obj->imode);
 240         if (!inode)
 241                 goto fail;
 242         if (IS_ERR(inode)) {
 243                 error = PTR_ERR(inode);
 244                 goto fail;
 245         }
 246
 247         error = gfs2_inode_refresh(GFS2_I(inode));
 248         if (error) {
 249                 iput(inode);
 250                 goto fail;
 251         }
 252
 253         error = -EIO;
 254         if (GFS2_I(inode)->i_di.di_flags & GFS2_DIF_SYSTEM) {
 255                 iput(inode);
 256                 goto fail;
 257         }
 258
 259         gfs2_glock_dq_uninit(&i_gh);
 260
 261 out_inode:
 262         dentry = d_alloc_anon(inode);
 263         if (!dentry) {
 264                 iput(inode);
 265                 return ERR_PTR(-ENOMEM);
 266         }
 267
 268         dentry->d_op = &gfs2_dops;
 269         return dentry;
 270
 271 fail_rgd:
 272         gfs2_glock_dq_uninit(&rgd_gh);
 273
 274 fail_rindex:
 275         gfs2_glock_dq_uninit(&ri_gh);
 276
 277 fail:
 278         gfs2_glock_dq_uninit(&i_gh);
 279         return ERR_PTR(error);
 280 }
 281
 282 struct export_operations gfs2_export_ops = {
 283         .decode_fh = gfs2_decode_fh,
 284         .encode_fh = gfs2_encode_fh,
 285         .get_name = gfs2_get_name,
 286         .get_parent = gfs2_get_parent,
 287         .get_dentry = gfs2_get_dentry,
 288 };
 289