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/sched.h>
  11 #include <linux/slab.h>
  12 #include <linux/spinlock.h>
  13 #include <linux/completion.h>
  14 #include <linux/buffer_head.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_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         if (fh_type != fh_len)
  42                 return NULL;
  43
  44         this            = &fh_obj.this;
  45         fh_obj.imode    = DT_UNKNOWN;
  46         memset(&parent, 0, sizeof(struct gfs2_inum));
  47
  48         switch (fh_type) {
  49         case GFS2_LARGE_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                 fh_obj.imode = be32_to_cpu(fh[8]);
  55         case GFS2_SMALL_FH_SIZE:
  56                 this->no_formal_ino = ((u64)be32_to_cpu(fh[0])) << 32;
  57                 this->no_formal_ino |= be32_to_cpu(fh[1]);
  58                 this->no_addr = ((u64)be32_to_cpu(fh[2])) << 32;
  59                 this->no_addr |= be32_to_cpu(fh[3]);
  60                 break;
  61         default:
  62                 return NULL;
  63         }
  64
  65         return gfs2_export_ops.find_exported_dentry(sb, &fh_obj, &parent,
  66                                                     acceptable, context);
  67 }
  68
  69 static int gfs2_encode_fh(struct dentry *dentry, __u32 *p, int *len,
  70                           int connectable)
  71 {
  72         __be32 *fh = (__force __be32 *)p;
  73         struct inode *inode = dentry->d_inode;
  74         struct super_block *sb = inode->i_sb;
  75         struct gfs2_inode *ip = GFS2_I(inode);
  76
  77         if (*len < GFS2_SMALL_FH_SIZE ||
  78             (connectable && *len < GFS2_LARGE_FH_SIZE))
  79                 return 255;
  80
  81         fh[0] = cpu_to_be32(ip->i_num.no_formal_ino >> 32);
  82         fh[1] = cpu_to_be32(ip->i_num.no_formal_ino & 0xFFFFFFFF);
  83         fh[2] = cpu_to_be32(ip->i_num.no_addr >> 32);
  84         fh[3] = cpu_to_be32(ip->i_num.no_addr & 0xFFFFFFFF);
  85         *len = GFS2_SMALL_FH_SIZE;
  86
  87         if (!connectable || inode == sb->s_root->d_inode)
  88                 return *len;
  89
  90         spin_lock(&dentry->d_lock);
  91         inode = dentry->d_parent->d_inode;
  92         ip = GFS2_I(inode);
  93         igrab(inode);
  94         spin_unlock(&dentry->d_lock);
  95
  96         fh[4] = cpu_to_be32(ip->i_num.no_formal_ino >> 32);
  97         fh[5] = cpu_to_be32(ip->i_num.no_formal_ino & 0xFFFFFFFF);
  98         fh[6] = cpu_to_be32(ip->i_num.no_addr >> 32);
  99         fh[7] = cpu_to_be32(ip->i_num.no_addr & 0xFFFFFFFF);
 100
 101         fh[8]  = cpu_to_be32(inode->i_mode);
 102         fh[9]  = 0;     /* pad to double word */
 103         *len = GFS2_LARGE_FH_SIZE;
 104
 105         iput(inode);
 106
 107         return *len;
 108 }
 109
 110 struct get_name_filldir {
 111         struct gfs2_inum_host inum;
 112         char *name;
 113 };
 114
 115 static int get_name_filldir(void *opaque, const char *name, unsigned int length,
 116                             u64 offset, struct gfs2_inum_host *inum,
 117                             unsigned int type)
 118 {
 119         struct get_name_filldir *gnfd = (struct get_name_filldir *)opaque;
 120
 121         if (!gfs2_inum_equal(inum, &gnfd->inum))
 122                 return 0;
 123
 124         memcpy(gnfd->name, name, length);
 125         gnfd->name[length] = 0;
 126
 127         return 1;
 128 }
 129
 130 static int gfs2_get_name(struct dentry *parent, char *name,
 131                          struct dentry *child)
 132 {
 133         struct inode *dir = parent->d_inode;
 134         struct inode *inode = child->d_inode;
 135         struct gfs2_inode *dip, *ip;
 136         struct get_name_filldir gnfd;
 137         struct gfs2_holder gh;
 138         u64 offset = 0;
 139         int error;
 140
 141         if (!dir)
 142                 return -EINVAL;
 143
 144         if (!S_ISDIR(dir->i_mode) || !inode)
 145                 return -EINVAL;
 146
 147         dip = GFS2_I(dir);
 148         ip = GFS2_I(inode);
 149
 150         *name = 0;
 151         gnfd.inum = ip->i_num;
 152         gnfd.name = name;
 153
 154         error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED, 0, &gh);
 155         if (error)
 156                 return error;
 157
 158         error = gfs2_dir_read(dir, &offset, &gnfd, get_name_filldir);
 159
 160         gfs2_glock_dq_uninit(&gh);
 161
 162         if (!error && !*name)
 163                 error = -ENOENT;
 164
 165         return error;
 166 }
 167
 168 static struct dentry *gfs2_get_parent(struct dentry *child)
 169 {
 170         struct qstr dotdot;
 171         struct inode *inode;
 172         struct dentry *dentry;
 173
 174         gfs2_str2qstr(&dotdot, "..");
 175         inode = gfs2_lookupi(child->d_inode, &dotdot, 1, NULL);
 176
 177         if (!inode)
 178                 return ERR_PTR(-ENOENT);
 179         /*
 180          * In case of an error, @inode carries the error value, and we
 181          * have to return that as a(n invalid) pointer to dentry.
 182          */
 183         if (IS_ERR(inode))
 184                 return ERR_PTR(PTR_ERR(inode));
 185
 186         dentry = d_alloc_anon(inode);
 187         if (!dentry) {
 188                 iput(inode);
 189                 return ERR_PTR(-ENOMEM);
 190         }
 191
 192         return dentry;
 193 }
 194
 195 static struct dentry *gfs2_get_dentry(struct super_block *sb, void *inum_obj)
 196 {
 197         struct gfs2_sbd *sdp = sb->s_fs_info;
 198         struct gfs2_fh_obj *fh_obj = (struct gfs2_fh_obj *)inum_obj;
 199         struct gfs2_inum_host *inum = &fh_obj->this;
 200         struct gfs2_holder i_gh, ri_gh, rgd_gh;
 201         struct gfs2_rgrpd *rgd;
 202         struct inode *inode;
 203         struct dentry *dentry;
 204         int error;
 205
 206         /* System files? */
 207
 208         inode = gfs2_ilookup(sb, inum);
 209         if (inode) {
 210                 if (GFS2_I(inode)->i_num.no_formal_ino != inum->no_formal_ino) {
 211                         iput(inode);
 212                         return ERR_PTR(-ESTALE);
 213                 }
 214                 goto out_inode;
 215         }
 216
 217         error = gfs2_glock_nq_num(sdp, inum->no_addr, &gfs2_inode_glops,
 218                                   LM_ST_SHARED, LM_FLAG_ANY | GL_LOCAL_EXCL,
 219                                   &i_gh);
 220         if (error)
 221                 return ERR_PTR(error);
 222
 223         error = gfs2_rindex_hold(sdp, &ri_gh);
 224         if (error)
 225                 goto fail;
 226
 227         error = -EINVAL;
 228         rgd = gfs2_blk2rgrpd(sdp, inum->no_addr);
 229         if (!rgd)
 230                 goto fail_rindex;
 231
 232         error = gfs2_glock_nq_init(rgd->rd_gl, LM_ST_SHARED, 0, &rgd_gh);
 233         if (error)
 234                 goto fail_rindex;
 235
 236         error = -ESTALE;
 237         if (gfs2_get_block_type(rgd, inum->no_addr) != GFS2_BLKST_DINODE)
 238                 goto fail_rgd;
 239
 240         gfs2_glock_dq_uninit(&rgd_gh);
 241         gfs2_glock_dq_uninit(&ri_gh);
 242
 243         inode = gfs2_inode_lookup(sb, inum, fh_obj->imode);
 244         if (!inode)
 245                 goto fail;
 246         if (IS_ERR(inode)) {
 247                 error = PTR_ERR(inode);
 248                 goto fail;
 249         }
 250
 251         error = gfs2_inode_refresh(GFS2_I(inode));
 252         if (error) {
 253                 iput(inode);
 254                 goto fail;
 255         }
 256
 257         error = -EIO;
 258         if (GFS2_I(inode)->i_di.di_flags & GFS2_DIF_SYSTEM) {
 259                 iput(inode);
 260                 goto fail;
 261         }
 262
 263         gfs2_glock_dq_uninit(&i_gh);
 264
 265 out_inode:
 266         dentry = d_alloc_anon(inode);
 267         if (!dentry) {
 268                 iput(inode);
 269                 return ERR_PTR(-ENOMEM);
 270         }
 271
 272         return dentry;
 273
 274 fail_rgd:
 275         gfs2_glock_dq_uninit(&rgd_gh);
 276
 277 fail_rindex:
 278         gfs2_glock_dq_uninit(&ri_gh);
 279
 280 fail:
 281         gfs2_glock_dq_uninit(&i_gh);
 282         return ERR_PTR(error);
 283 }
 284
 285 struct export_operations gfs2_export_ops = {
 286         .decode_fh = gfs2_decode_fh,
 287         .encode_fh = gfs2_encode_fh,
 288         .get_name = gfs2_get_name,
 289         .get_parent = gfs2_get_parent,
 290         .get_dentry = gfs2_get_dentry,
 291 };
 292