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