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 "super.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 #define GFS2_OLD_FH_SIZE 10
  32
  33 static int gfs2_encode_fh(struct dentry *dentry, __u32 *p, int *len,
  34                           int connectable)
  35 {
  36         __be32 *fh = (__force __be32 *)p;
  37         struct inode *inode = dentry->d_inode;
  38         struct super_block *sb = inode->i_sb;
  39         struct gfs2_inode *ip = GFS2_I(inode);
  40
  41         if (*len < GFS2_SMALL_FH_SIZE ||
  42             (connectable && *len < GFS2_LARGE_FH_SIZE))
  43                 return 255;
  44
  45         fh[0] = cpu_to_be32(ip->i_no_formal_ino >> 32);
  46         fh[1] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
  47         fh[2] = cpu_to_be32(ip->i_no_addr >> 32);
  48         fh[3] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
  49         *len = GFS2_SMALL_FH_SIZE;
  50
  51         if (!connectable || inode == sb->s_root->d_inode)
  52                 return *len;
  53
  54         spin_lock(&dentry->d_lock);
  55         inode = dentry->d_parent->d_inode;
  56         ip = GFS2_I(inode);
  57         igrab(inode);
  58         spin_unlock(&dentry->d_lock);
  59
  60         fh[4] = cpu_to_be32(ip->i_no_formal_ino >> 32);
  61         fh[5] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
  62         fh[6] = cpu_to_be32(ip->i_no_addr >> 32);
  63         fh[7] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
  64         *len = GFS2_LARGE_FH_SIZE;
  65
  66         iput(inode);
  67
  68         return *len;
  69 }
  70
  71 struct get_name_filldir {
  72         struct gfs2_inum_host inum;
  73         char *name;
  74 };
  75
  76 static int get_name_filldir(void *opaque, const char *name, int length,
  77                             loff_t offset, u64 inum, unsigned int type)
  78 {
  79         struct get_name_filldir *gnfd = opaque;
  80
  81         if (inum != gnfd->inum.no_addr)
  82                 return 0;
  83
  84         memcpy(gnfd->name, name, length);
  85         gnfd->name[length] = 0;
  86
  87         return 1;
  88 }
  89
  90 static int gfs2_get_name(struct dentry *parent, char *name,
  91                          struct dentry *child)
  92 {
  93         struct inode *dir = parent->d_inode;
  94         struct inode *inode = child->d_inode;
  95         struct gfs2_inode *dip, *ip;
  96         struct get_name_filldir gnfd;
  97         struct gfs2_holder gh;
  98         u64 offset = 0;
  99         int error;
 100
 101         if (!dir)
 102                 return -EINVAL;
 103
 104         if (!S_ISDIR(dir->i_mode) || !inode)
 105                 return -EINVAL;
 106
 107         dip = GFS2_I(dir);
 108         ip = GFS2_I(inode);
 109
 110         *name = 0;
 111         gnfd.inum.no_addr = ip->i_no_addr;
 112         gnfd.inum.no_formal_ino = ip->i_no_formal_ino;
 113         gnfd.name = name;
 114
 115         error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED, 0, &gh);
 116         if (error)
 117                 return error;
 118
 119         error = gfs2_dir_read(dir, &offset, &gnfd, get_name_filldir);
 120
 121         gfs2_glock_dq_uninit(&gh);
 122
 123         if (!error && !*name)
 124                 error = -ENOENT;
 125
 126         return error;
 127 }
 128
 129 static struct dentry *gfs2_get_parent(struct dentry *child)
 130 {
 131         struct qstr dotdot;
 132         struct dentry *dentry;
 133
 134         /*
 135          * XXX(hch): it would be a good idea to keep this around as a
 136          *           static variable.
 137          */
 138         gfs2_str2qstr(&dotdot, "..");
 139
 140         dentry = d_obtain_alias(gfs2_lookupi(child->d_inode, &dotdot, 1));
 141         if (!IS_ERR(dentry))
 142                 dentry->d_op = &gfs2_dops;
 143         return dentry;
 144 }
 145
 146 static struct dentry *gfs2_get_dentry(struct super_block *sb,
 147                 struct gfs2_inum_host *inum)
 148 {
 149         struct gfs2_sbd *sdp = sb->s_fs_info;
 150         struct gfs2_holder i_gh, ri_gh, rgd_gh;
 151         struct gfs2_rgrpd *rgd;
 152         struct inode *inode;
 153         struct dentry *dentry;
 154         int error;
 155
 156         /* System files? */
 157
 158         inode = gfs2_ilookup(sb, inum->no_addr);
 159         if (inode) {
 160                 if (GFS2_I(inode)->i_no_formal_ino != inum->no_formal_ino) {
 161                         iput(inode);
 162                         return ERR_PTR(-ESTALE);
 163                 }
 164                 goto out_inode;
 165         }
 166
 167         error = gfs2_glock_nq_num(sdp, inum->no_addr, &gfs2_inode_glops,
 168                                   LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
 169         if (error)
 170                 return ERR_PTR(error);
 171
 172         error = gfs2_rindex_hold(sdp, &ri_gh);
 173         if (error)
 174                 goto fail;
 175
 176         error = -EINVAL;
 177         rgd = gfs2_blk2rgrpd(sdp, inum->no_addr);
 178         if (!rgd)
 179                 goto fail_rindex;
 180
 181         error = gfs2_glock_nq_init(rgd->rd_gl, LM_ST_SHARED, 0, &rgd_gh);
 182         if (error)
 183                 goto fail_rindex;
 184
 185         error = -ESTALE;
 186         if (gfs2_get_block_type(rgd, inum->no_addr) != GFS2_BLKST_DINODE)
 187                 goto fail_rgd;
 188
 189         gfs2_glock_dq_uninit(&rgd_gh);
 190         gfs2_glock_dq_uninit(&ri_gh);
 191
 192         inode = gfs2_inode_lookup(sb, DT_UNKNOWN,
 193                                         inum->no_addr,
 194                                         0, 0);
 195         if (IS_ERR(inode)) {
 196                 error = PTR_ERR(inode);
 197                 goto fail;
 198         }
 199
 200         error = gfs2_inode_refresh(GFS2_I(inode));
 201         if (error) {
 202                 iput(inode);
 203                 goto fail;
 204         }
 205
 206         /* Pick up the works we bypass in gfs2_inode_lookup */
 207         if (inode->i_state & I_NEW)
 208                 gfs2_set_iop(inode);
 209
 210         if (GFS2_I(inode)->i_no_formal_ino != inum->no_formal_ino) {
 211                 iput(inode);
 212                 goto fail;
 213         }
 214
 215         error = -EIO;
 216         if (GFS2_I(inode)->i_diskflags & GFS2_DIF_SYSTEM) {
 217                 iput(inode);
 218                 goto fail;
 219         }
 220
 221         gfs2_glock_dq_uninit(&i_gh);
 222
 223 out_inode:
 224         dentry = d_obtain_alias(inode);
 225         if (!IS_ERR(dentry))
 226                 dentry->d_op = &gfs2_dops;
 227         return dentry;
 228
 229 fail_rgd:
 230         gfs2_glock_dq_uninit(&rgd_gh);
 231
 232 fail_rindex:
 233         gfs2_glock_dq_uninit(&ri_gh);
 234
 235 fail:
 236         gfs2_glock_dq_uninit(&i_gh);
 237         return ERR_PTR(error);
 238 }
 239
 240 static struct dentry *gfs2_fh_to_dentry(struct super_block *sb, struct fid *fid,
 241                 int fh_len, int fh_type)
 242 {
 243         struct gfs2_inum_host this;
 244         __be32 *fh = (__force __be32 *)fid->raw;
 245
 246         switch (fh_type) {
 247         case GFS2_SMALL_FH_SIZE:
 248         case GFS2_LARGE_FH_SIZE:
 249         case GFS2_OLD_FH_SIZE:
 250                 this.no_formal_ino = ((u64)be32_to_cpu(fh[0])) << 32;
 251                 this.no_formal_ino |= be32_to_cpu(fh[1]);
 252                 this.no_addr = ((u64)be32_to_cpu(fh[2])) << 32;
 253                 this.no_addr |= be32_to_cpu(fh[3]);
 254                 return gfs2_get_dentry(sb, &this);
 255         default:
 256                 return NULL;
 257         }
 258 }
 259
 260 static struct dentry *gfs2_fh_to_parent(struct super_block *sb, struct fid *fid,
 261                 int fh_len, int fh_type)
 262 {
 263         struct gfs2_inum_host parent;
 264         __be32 *fh = (__force __be32 *)fid->raw;
 265
 266         switch (fh_type) {
 267         case GFS2_LARGE_FH_SIZE:
 268         case GFS2_OLD_FH_SIZE:
 269                 parent.no_formal_ino = ((u64)be32_to_cpu(fh[4])) << 32;
 270                 parent.no_formal_ino |= be32_to_cpu(fh[5]);
 271                 parent.no_addr = ((u64)be32_to_cpu(fh[6])) << 32;
 272                 parent.no_addr |= be32_to_cpu(fh[7]);
 273                 return gfs2_get_dentry(sb, &parent);
 274         default:
 275                 return NULL;
 276         }
 277 }
 278
 279 const struct export_operations gfs2_export_ops = {
 280         .encode_fh = gfs2_encode_fh,
 281         .fh_to_dentry = gfs2_fh_to_dentry,
 282         .fh_to_parent = gfs2_fh_to_parent,
 283         .get_name = gfs2_get_name,
 284         .get_parent = gfs2_get_parent,
 285 };
 286