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 #define GFS2_OLD_FH_SIZE 10
  32
  33 static struct dentry *gfs2_decode_fh(struct super_block *sb,
  34                                      __u32 *p,
  35                                      int fh_len,
  36                                      int fh_type,
  37                                      int (*acceptable)(void *context,
  38                                                        struct dentry *dentry),
  39                                      void *context)
  40 {
  41         __be32 *fh = (__force __be32 *)p;
  42         struct gfs2_inum_host inum, parent;
  43
  44         memset(&parent, 0, sizeof(struct gfs2_inum));
  45
  46         switch (fh_len) {
  47         case GFS2_LARGE_FH_SIZE:
  48         case GFS2_OLD_FH_SIZE:
  49                 parent.no_formal_ino = ((u64)be32_to_cpu(fh[4])) << 32;
  50                 parent.no_formal_ino |= be32_to_cpu(fh[5]);
  51                 parent.no_addr = ((u64)be32_to_cpu(fh[6])) << 32;
  52                 parent.no_addr |= be32_to_cpu(fh[7]);
  53         case GFS2_SMALL_FH_SIZE:
  54                 inum.no_formal_ino = ((u64)be32_to_cpu(fh[0])) << 32;
  55                 inum.no_formal_ino |= be32_to_cpu(fh[1]);
  56                 inum.no_addr = ((u64)be32_to_cpu(fh[2])) << 32;
  57                 inum.no_addr |= be32_to_cpu(fh[3]);
  58                 break;
  59         default:
  60                 return NULL;
  61         }
  62
  63         return gfs2_export_ops.find_exported_dentry(sb, &inum, &parent,
  64                                                     acceptable, context);
  65 }
  66
  67 static int gfs2_encode_fh(struct dentry *dentry, __u32 *p, int *len,
  68                           int connectable)
  69 {
  70         __be32 *fh = (__force __be32 *)p;
  71         struct inode *inode = dentry->d_inode;
  72         struct super_block *sb = inode->i_sb;
  73         struct gfs2_inode *ip = GFS2_I(inode);
  74
  75         if (*len < GFS2_SMALL_FH_SIZE ||
  76             (connectable && *len < GFS2_LARGE_FH_SIZE))
  77                 return 255;
  78
  79         fh[0] = cpu_to_be32(ip->i_no_formal_ino >> 32);
  80         fh[1] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
  81         fh[2] = cpu_to_be32(ip->i_no_addr >> 32);
  82         fh[3] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
  83         *len = GFS2_SMALL_FH_SIZE;
  84
  85         if (!connectable || inode == sb->s_root->d_inode)
  86                 return *len;
  87
  88         spin_lock(&dentry->d_lock);
  89         inode = dentry->d_parent->d_inode;
  90         ip = GFS2_I(inode);
  91         igrab(inode);
  92         spin_unlock(&dentry->d_lock);
  93
  94         fh[4] = cpu_to_be32(ip->i_no_formal_ino >> 32);
  95         fh[5] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
  96         fh[6] = cpu_to_be32(ip->i_no_addr >> 32);
  97         fh[7] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
  98         *len = GFS2_LARGE_FH_SIZE;
  99
 100         iput(inode);
 101
 102         return *len;
 103 }
 104
 105 struct get_name_filldir {
 106         struct gfs2_inum_host inum;
 107         char *name;
 108 };
 109
 110 static int get_name_filldir(void *opaque, const char *name, int length,
 111                             loff_t offset, u64 inum, unsigned int type)
 112 {
 113         struct get_name_filldir *gnfd = opaque;
 114
 115         if (inum != gnfd->inum.no_addr)
 116                 return 0;
 117
 118         memcpy(gnfd->name, name, length);
 119         gnfd->name[length] = 0;
 120
 121         return 1;
 122 }
 123
 124 static int gfs2_get_name(struct dentry *parent, char *name,
 125                          struct dentry *child)
 126 {
 127         struct inode *dir = parent->d_inode;
 128         struct inode *inode = child->d_inode;
 129         struct gfs2_inode *dip, *ip;
 130         struct get_name_filldir gnfd;
 131         struct gfs2_holder gh;
 132         u64 offset = 0;
 133         int error;
 134
 135         if (!dir)
 136                 return -EINVAL;
 137
 138         if (!S_ISDIR(dir->i_mode) || !inode)
 139                 return -EINVAL;
 140
 141         dip = GFS2_I(dir);
 142         ip = GFS2_I(inode);
 143
 144         *name = 0;
 145         gnfd.inum.no_addr = ip->i_no_addr;
 146         gnfd.inum.no_formal_ino = ip->i_no_formal_ino;
 147         gnfd.name = name;
 148
 149         error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED, 0, &gh);
 150         if (error)
 151                 return error;
 152
 153         error = gfs2_dir_read(dir, &offset, &gnfd, get_name_filldir);
 154
 155         gfs2_glock_dq_uninit(&gh);
 156
 157         if (!error && !*name)
 158                 error = -ENOENT;
 159
 160         return error;
 161 }
 162
 163 static struct dentry *gfs2_get_parent(struct dentry *child)
 164 {
 165         struct qstr dotdot;
 166         struct inode *inode;
 167         struct dentry *dentry;
 168
 169         gfs2_str2qstr(&dotdot, "..");
 170         inode = gfs2_lookupi(child->d_inode, &dotdot, 1, NULL);
 171
 172         if (!inode)
 173                 return ERR_PTR(-ENOENT);
 174         /*
 175          * In case of an error, @inode carries the error value, and we
 176          * have to return that as a(n invalid) pointer to dentry.
 177          */
 178         if (IS_ERR(inode))
 179                 return ERR_PTR(PTR_ERR(inode));
 180
 181         dentry = d_alloc_anon(inode);
 182         if (!dentry) {
 183                 iput(inode);
 184                 return ERR_PTR(-ENOMEM);
 185         }
 186
 187         dentry->d_op = &gfs2_dops;
 188         return dentry;
 189 }
 190
 191 static struct dentry *gfs2_get_dentry(struct super_block *sb, void *inum_obj)
 192 {
 193         struct gfs2_sbd *sdp = sb->s_fs_info;
 194         struct gfs2_inum_host *inum = inum_obj;
 195         struct gfs2_holder i_gh, ri_gh, rgd_gh;
 196         struct gfs2_rgrpd *rgd;
 197         struct inode *inode;
 198         struct dentry *dentry;
 199         int error;
 200
 201         /* System files? */
 202
 203         inode = gfs2_ilookup(sb, inum->no_addr);
 204         if (inode) {
 205                 if (GFS2_I(inode)->i_no_formal_ino != inum->no_formal_ino) {
 206                         iput(inode);
 207                         return ERR_PTR(-ESTALE);
 208                 }
 209                 goto out_inode;
 210         }
 211
 212         error = gfs2_glock_nq_num(sdp, inum->no_addr, &gfs2_inode_glops,
 213                                   LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
 214         if (error)
 215                 return ERR_PTR(error);
 216
 217         error = gfs2_rindex_hold(sdp, &ri_gh);
 218         if (error)
 219                 goto fail;
 220
 221         error = -EINVAL;
 222         rgd = gfs2_blk2rgrpd(sdp, inum->no_addr);
 223         if (!rgd)
 224                 goto fail_rindex;
 225
 226         error = gfs2_glock_nq_init(rgd->rd_gl, LM_ST_SHARED, 0, &rgd_gh);
 227         if (error)
 228                 goto fail_rindex;
 229
 230         error = -ESTALE;
 231         if (gfs2_get_block_type(rgd, inum->no_addr) != GFS2_BLKST_DINODE)
 232                 goto fail_rgd;
 233
 234         gfs2_glock_dq_uninit(&rgd_gh);
 235         gfs2_glock_dq_uninit(&ri_gh);
 236
 237         inode = gfs2_inode_lookup(sb, DT_UNKNOWN,
 238                                         inum->no_addr,
 239                                         0);
 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         /* Pick up the works we bypass in gfs2_inode_lookup */
 254         if (inode->i_state & I_NEW)
 255                 gfs2_set_iop(inode);
 256
 257         if (GFS2_I(inode)->i_no_formal_ino != inum->no_formal_ino) {
 258                 iput(inode);
 259                 goto fail;
 260         }
 261
 262         error = -EIO;
 263         if (GFS2_I(inode)->i_di.di_flags & GFS2_DIF_SYSTEM) {
 264                 iput(inode);
 265                 goto fail;
 266         }
 267
 268         gfs2_glock_dq_uninit(&i_gh);
 269
 270 out_inode:
 271         dentry = d_alloc_anon(inode);
 272         if (!dentry) {
 273                 iput(inode);
 274                 return ERR_PTR(-ENOMEM);
 275         }
 276
 277         dentry->d_op = &gfs2_dops;
 278         return dentry;
 279
 280 fail_rgd:
 281         gfs2_glock_dq_uninit(&rgd_gh);
 282
 283 fail_rindex:
 284         gfs2_glock_dq_uninit(&ri_gh);
 285
 286 fail:
 287         gfs2_glock_dq_uninit(&i_gh);
 288         return ERR_PTR(error);
 289 }
 290
 291 struct export_operations gfs2_export_ops = {
 292         .decode_fh = gfs2_decode_fh,
 293         .encode_fh = gfs2_encode_fh,
 294         .get_name = gfs2_get_name,
 295         .get_parent = gfs2_get_parent,
 296         .get_dentry = gfs2_get_dentry,
 297 };
 298