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 int gfs2_encode_fh(struct dentry *dentry, __u32 *p, int *len,
  35                           int connectable)
  36 {
  37         __be32 *fh = (__force __be32 *)p;
  38         struct inode *inode = dentry->d_inode;
  39         struct super_block *sb = inode->i_sb;
  40         struct gfs2_inode *ip = GFS2_I(inode);
  41
  42         if (*len < GFS2_SMALL_FH_SIZE ||
  43             (connectable && *len < GFS2_LARGE_FH_SIZE))
  44                 return 255;
  45
  46         fh[0] = cpu_to_be32(ip->i_no_formal_ino >> 32);
  47         fh[1] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
  48         fh[2] = cpu_to_be32(ip->i_no_addr >> 32);
  49         fh[3] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
  50         *len = GFS2_SMALL_FH_SIZE;
  51
  52         if (!connectable || inode == sb->s_root->d_inode)
  53                 return *len;
  54
  55         spin_lock(&dentry->d_lock);
  56         inode = dentry->d_parent->d_inode;
  57         ip = GFS2_I(inode);
  58         igrab(inode);
  59         spin_unlock(&dentry->d_lock);
  60
  61         fh[4] = cpu_to_be32(ip->i_no_formal_ino >> 32);
  62         fh[5] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
  63         fh[6] = cpu_to_be32(ip->i_no_addr >> 32);
  64         fh[7] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
  65         *len = GFS2_LARGE_FH_SIZE;
  66
  67         iput(inode);
  68
  69         return *len;
  70 }
  71
  72 struct get_name_filldir {
  73         struct gfs2_inum_host inum;
  74         char *name;
  75 };
  76
  77 static int get_name_filldir(void *opaque, const char *name, int length,
  78                             loff_t offset, u64 inum, unsigned int type)
  79 {
  80         struct get_name_filldir *gnfd = opaque;
  81
  82         if (inum != gnfd->inum.no_addr)
  83                 return 0;
  84
  85         memcpy(gnfd->name, name, length);
  86         gnfd->name[length] = 0;
  87
  88         return 1;
  89 }
  90
  91 static int gfs2_get_name(struct dentry *parent, char *name,
  92                          struct dentry *child)
  93 {
  94         struct inode *dir = parent->d_inode;
  95         struct inode *inode = child->d_inode;
  96         struct gfs2_inode *dip, *ip;
  97         struct get_name_filldir gnfd;
  98         struct gfs2_holder gh;
  99         u64 offset = 0;
 100         int error;
 101
 102         if (!dir)
 103                 return -EINVAL;
 104
 105         if (!S_ISDIR(dir->i_mode) || !inode)
 106                 return -EINVAL;
 107
 108         dip = GFS2_I(dir);
 109         ip = GFS2_I(inode);
 110
 111         *name = 0;
 112         gnfd.inum.no_addr = ip->i_no_addr;
 113         gnfd.inum.no_formal_ino = ip->i_no_formal_ino;
 114         gnfd.name = name;
 115
 116         error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED, 0, &gh);
 117         if (error)
 118                 return error;
 119
 120         error = gfs2_dir_read(dir, &offset, &gnfd, get_name_filldir);
 121
 122         gfs2_glock_dq_uninit(&gh);
 123
 124         if (!error && !*name)
 125                 error = -ENOENT;
 126
 127         return error;
 128 }
 129
 130 static struct dentry *gfs2_get_parent(struct dentry *child)
 131 {
 132         struct qstr dotdot;
 133         struct dentry *dentry;
 134
 135         /*
 136          * XXX(hch): it would be a good idea to keep this around as a
 137          *           static variable.
 138          */
 139         gfs2_str2qstr(&dotdot, "..");
 140
 141         dentry = d_obtain_alias(gfs2_lookupi(child->d_inode, &dotdot, 1));
 142         if (!IS_ERR(dentry))
 143                 dentry->d_op = &gfs2_dops;
 144         return dentry;
 145 }
 146
 147 static struct dentry *gfs2_get_dentry(struct super_block *sb,
 148                 struct gfs2_inum_host *inum)
 149 {
 150         struct gfs2_sbd *sdp = sb->s_fs_info;
 151         struct gfs2_holder i_gh, ri_gh, rgd_gh;
 152         struct gfs2_rgrpd *rgd;
 153         struct inode *inode;
 154         struct dentry *dentry;
 155         int error;
 156
 157         /* System files? */
 158
 159         inode = gfs2_ilookup(sb, inum->no_addr);
 160         if (inode) {
 161                 if (GFS2_I(inode)->i_no_formal_ino != inum->no_formal_ino) {
 162                         iput(inode);
 163                         return ERR_PTR(-ESTALE);
 164                 }
 165                 goto out_inode;
 166         }
 167
 168         error = gfs2_glock_nq_num(sdp, inum->no_addr, &gfs2_inode_glops,
 169                                   LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
 170         if (error)
 171                 return ERR_PTR(error);
 172
 173         error = gfs2_rindex_hold(sdp, &ri_gh);
 174         if (error)
 175                 goto fail;
 176
 177         error = -EINVAL;
 178         rgd = gfs2_blk2rgrpd(sdp, inum->no_addr);
 179         if (!rgd)
 180                 goto fail_rindex;
 181
 182         error = gfs2_glock_nq_init(rgd->rd_gl, LM_ST_SHARED, 0, &rgd_gh);
 183         if (error)
 184                 goto fail_rindex;
 185
 186         error = -ESTALE;
 187         if (gfs2_get_block_type(rgd, inum->no_addr) != GFS2_BLKST_DINODE)
 188                 goto fail_rgd;
 189
 190         gfs2_glock_dq_uninit(&rgd_gh);
 191         gfs2_glock_dq_uninit(&ri_gh);
 192
 193         inode = gfs2_inode_lookup(sb, DT_UNKNOWN,
 194                                         inum->no_addr,
 195                                         0, 0);
 196         if (IS_ERR(inode)) {
 197                 error = PTR_ERR(inode);
 198                 goto fail;
 199         }
 200
 201         error = gfs2_inode_refresh(GFS2_I(inode));
 202         if (error) {
 203                 iput(inode);
 204                 goto fail;
 205         }
 206
 207         /* Pick up the works we bypass in gfs2_inode_lookup */
 208         if (inode->i_state & I_NEW)
 209                 gfs2_set_iop(inode);
 210
 211         if (GFS2_I(inode)->i_no_formal_ino != inum->no_formal_ino) {
 212                 iput(inode);
 213                 goto fail;
 214         }
 215
 216         error = -EIO;
 217         if (GFS2_I(inode)->i_di.di_flags & GFS2_DIF_SYSTEM) {
 218                 iput(inode);
 219                 goto fail;
 220         }
 221
 222         gfs2_glock_dq_uninit(&i_gh);
 223
 224 out_inode:
 225         dentry = d_obtain_alias(inode);
 226         if (!IS_ERR(dentry))
 227                 dentry->d_op = &gfs2_dops;
 228         return dentry;
 229
 230 fail_rgd:
 231         gfs2_glock_dq_uninit(&rgd_gh);
 232
 233 fail_rindex:
 234         gfs2_glock_dq_uninit(&ri_gh);
 235
 236 fail:
 237         gfs2_glock_dq_uninit(&i_gh);
 238         return ERR_PTR(error);
 239 }
 240
 241 static struct dentry *gfs2_fh_to_dentry(struct super_block *sb, struct fid *fid,
 242                 int fh_len, int fh_type)
 243 {
 244         struct gfs2_inum_host this;
 245         __be32 *fh = (__force __be32 *)fid->raw;
 246
 247         switch (fh_type) {
 248         case GFS2_SMALL_FH_SIZE:
 249         case GFS2_LARGE_FH_SIZE:
 250         case GFS2_OLD_FH_SIZE:
 251                 this.no_formal_ino = ((u64)be32_to_cpu(fh[0])) << 32;
 252                 this.no_formal_ino |= be32_to_cpu(fh[1]);
 253                 this.no_addr = ((u64)be32_to_cpu(fh[2])) << 32;
 254                 this.no_addr |= be32_to_cpu(fh[3]);
 255                 return gfs2_get_dentry(sb, &this);
 256         default:
 257                 return NULL;
 258         }
 259 }
 260
 261 static struct dentry *gfs2_fh_to_parent(struct super_block *sb, struct fid *fid,
 262                 int fh_len, int fh_type)
 263 {
 264         struct gfs2_inum_host parent;
 265         __be32 *fh = (__force __be32 *)fid->raw;
 266
 267         switch (fh_type) {
 268         case GFS2_LARGE_FH_SIZE:
 269         case GFS2_OLD_FH_SIZE:
 270                 parent.no_formal_ino = ((u64)be32_to_cpu(fh[4])) << 32;
 271                 parent.no_formal_ino |= be32_to_cpu(fh[5]);
 272                 parent.no_addr = ((u64)be32_to_cpu(fh[6])) << 32;
 273                 parent.no_addr |= be32_to_cpu(fh[7]);
 274                 return gfs2_get_dentry(sb, &parent);
 275         default:
 276                 return NULL;
 277         }
 278 }
 279
 280 const struct export_operations gfs2_export_ops = {
 281         .encode_fh = gfs2_encode_fh,
 282         .fh_to_dentry = gfs2_fh_to_dentry,
 283         .fh_to_parent = gfs2_fh_to_parent,
 284         .get_name = gfs2_get_name,
 285         .get_parent = gfs2_get_parent,
 286 };
 287