fs/gfs2/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/spinlock.h>
  11 #include <linux/completion.h>
  12 #include <linux/buffer_head.h>
  13 #include <linux/exportfs.h>
  14 #include <linux/gfs2_ondisk.h>
  15 #include <linux/crc32.h>
  16
  17 #include "gfs2.h"
  18 #include "incore.h"
  19 #include "dir.h"
  20 #include "glock.h"
  21 #include "glops.h"
  22 #include "inode.h"
  23 #include "super.h"
  24 #include "rgrp.h"
  25 #include "util.h"
  26
  27 #define GFS2_SMALL_FH_SIZE 4
  28 #define GFS2_LARGE_FH_SIZE 8
  29 #define GFS2_OLD_FH_SIZE 10
  30
  31 static int gfs2_encode_fh(struct dentry *dentry, __u32 *p, int *len,
  32                           int connectable)
  33 {
  34         __be32 *fh = (__force __be32 *)p;
  35         struct inode *inode = dentry->d_inode;
  36         struct super_block *sb = inode->i_sb;
  37         struct gfs2_inode *ip = GFS2_I(inode);
  38
  39         if (*len < GFS2_SMALL_FH_SIZE ||
  40             (connectable && *len < GFS2_LARGE_FH_SIZE))
  41                 return 255;
  42
  43         fh[0] = cpu_to_be32(ip->i_no_formal_ino >> 32);
  44         fh[1] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
  45         fh[2] = cpu_to_be32(ip->i_no_addr >> 32);
  46         fh[3] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
  47         *len = GFS2_SMALL_FH_SIZE;
  48
  49         if (!connectable || inode == sb->s_root->d_inode)
  50                 return *len;
  51
  52         spin_lock(&dentry->d_lock);
  53         inode = dentry->d_parent->d_inode;
  54         ip = GFS2_I(inode);
  55         igrab(inode);
  56         spin_unlock(&dentry->d_lock);
  57
  58         fh[4] = cpu_to_be32(ip->i_no_formal_ino >> 32);
  59         fh[5] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
  60         fh[6] = cpu_to_be32(ip->i_no_addr >> 32);
  61         fh[7] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
  62         *len = GFS2_LARGE_FH_SIZE;
  63
  64         iput(inode);
  65
  66         return *len;
  67 }
  68
  69 struct get_name_filldir {
  70         struct gfs2_inum_host inum;
  71         char *name;
  72 };
  73
  74 static int get_name_filldir(void *opaque, const char *name, int length,
  75                             loff_t offset, u64 inum, unsigned int type)
  76 {
  77         struct get_name_filldir *gnfd = opaque;
  78
  79         if (inum != gnfd->inum.no_addr)
  80                 return 0;
  81
  82         memcpy(gnfd->name, name, length);
  83         gnfd->name[length] = 0;
  84
  85         return 1;
  86 }
  87
  88 static int gfs2_get_name(struct dentry *parent, char *name,
  89                          struct dentry *child)
  90 {
  91         struct inode *dir = parent->d_inode;
  92         struct inode *inode = child->d_inode;
  93         struct gfs2_inode *dip, *ip;
  94         struct get_name_filldir gnfd;
  95         struct gfs2_holder gh;
  96         u64 offset = 0;
  97         int error;
  98
  99         if (!dir)
 100                 return -EINVAL;
 101
 102         if (!S_ISDIR(dir->i_mode) || !inode)
 103                 return -EINVAL;
 104
 105         dip = GFS2_I(dir);
 106         ip = GFS2_I(inode);
 107
 108         *name = 0;
 109         gnfd.inum.no_addr = ip->i_no_addr;
 110         gnfd.inum.no_formal_ino = ip->i_no_formal_ino;
 111         gnfd.name = name;
 112
 113         error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED, 0, &gh);
 114         if (error)
 115                 return error;
 116
 117         error = gfs2_dir_read(dir, &offset, &gnfd, get_name_filldir);
 118
 119         gfs2_glock_dq_uninit(&gh);
 120
 121         if (!error && !*name)
 122                 error = -ENOENT;
 123
 124         return error;
 125 }
 126
 127 static struct dentry *gfs2_get_parent(struct dentry *child)
 128 {
 129         struct qstr dotdot;
 130         struct dentry *dentry;
 131
 132         /*
 133          * XXX(hch): it would be a good idea to keep this around as a
 134          *           static variable.
 135          */
 136         gfs2_str2qstr(&dotdot, "..");
 137
 138         dentry = d_obtain_alias(gfs2_lookupi(child->d_inode, &dotdot, 1));
 139         if (!IS_ERR(dentry))
 140                 dentry->d_op = &gfs2_dops;
 141         return dentry;
 142 }
 143
 144 static struct dentry *gfs2_get_dentry(struct super_block *sb,
 145                                       struct gfs2_inum_host *inum)
 146 {
 147         struct gfs2_sbd *sdp = sb->s_fs_info;
 148         struct gfs2_holder i_gh;
 149         struct inode *inode;
 150         struct dentry *dentry;
 151         int error;
 152
 153         inode = gfs2_ilookup(sb, inum->no_addr);
 154         if (inode) {
 155                 if (GFS2_I(inode)->i_no_formal_ino != inum->no_formal_ino) {
 156                         iput(inode);
 157                         return ERR_PTR(-ESTALE);
 158                 }
 159                 goto out_inode;
 160         }
 161
 162         error = gfs2_glock_nq_num(sdp, inum->no_addr, &gfs2_inode_glops,
 163                                   LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
 164         if (error)
 165                 return ERR_PTR(error);
 166
 167         error = gfs2_check_blk_type(sdp, inum->no_addr, GFS2_BLKST_DINODE);
 168         if (error)
 169                 goto fail;
 170
 171         inode = gfs2_inode_lookup(sb, DT_UNKNOWN, inum->no_addr, 0);
 172         if (IS_ERR(inode)) {
 173                 error = PTR_ERR(inode);
 174                 goto fail;
 175         }
 176
 177         error = gfs2_inode_refresh(GFS2_I(inode));
 178         if (error) {
 179                 iput(inode);
 180                 goto fail;
 181         }
 182
 183         /* Pick up the works we bypass in gfs2_inode_lookup */
 184         if (inode->i_state & I_NEW)
 185                 gfs2_set_iop(inode);
 186
 187         if (GFS2_I(inode)->i_no_formal_ino != inum->no_formal_ino) {
 188                 iput(inode);
 189                 goto fail;
 190         }
 191
 192         error = -EIO;
 193         if (GFS2_I(inode)->i_diskflags & GFS2_DIF_SYSTEM) {
 194                 iput(inode);
 195                 goto fail;
 196         }
 197
 198         gfs2_glock_dq_uninit(&i_gh);
 199
 200 out_inode:
 201         dentry = d_obtain_alias(inode);
 202         if (!IS_ERR(dentry))
 203                 dentry->d_op = &gfs2_dops;
 204         return dentry;
 205 fail:
 206         gfs2_glock_dq_uninit(&i_gh);
 207         return ERR_PTR(error);
 208 }
 209
 210 static struct dentry *gfs2_fh_to_dentry(struct super_block *sb, struct fid *fid,
 211                 int fh_len, int fh_type)
 212 {
 213         struct gfs2_inum_host this;
 214         __be32 *fh = (__force __be32 *)fid->raw;
 215
 216         switch (fh_type) {
 217         case GFS2_SMALL_FH_SIZE:
 218         case GFS2_LARGE_FH_SIZE:
 219         case GFS2_OLD_FH_SIZE:
 220                 this.no_formal_ino = ((u64)be32_to_cpu(fh[0])) << 32;
 221                 this.no_formal_ino |= be32_to_cpu(fh[1]);
 222                 this.no_addr = ((u64)be32_to_cpu(fh[2])) << 32;
 223                 this.no_addr |= be32_to_cpu(fh[3]);
 224                 return gfs2_get_dentry(sb, &this);
 225         default:
 226                 return NULL;
 227         }
 228 }
 229
 230 static struct dentry *gfs2_fh_to_parent(struct super_block *sb, struct fid *fid,
 231                 int fh_len, int fh_type)
 232 {
 233         struct gfs2_inum_host parent;
 234         __be32 *fh = (__force __be32 *)fid->raw;
 235
 236         switch (fh_type) {
 237         case GFS2_LARGE_FH_SIZE:
 238         case GFS2_OLD_FH_SIZE:
 239                 parent.no_formal_ino = ((u64)be32_to_cpu(fh[4])) << 32;
 240                 parent.no_formal_ino |= be32_to_cpu(fh[5]);
 241                 parent.no_addr = ((u64)be32_to_cpu(fh[6])) << 32;
 242                 parent.no_addr |= be32_to_cpu(fh[7]);
 243                 return gfs2_get_dentry(sb, &parent);
 244         default:
 245                 return NULL;
 246         }
 247 }
 248
 249 const struct export_operations gfs2_export_ops = {
 250         .encode_fh = gfs2_encode_fh,
 251         .fh_to_dentry = gfs2_fh_to_dentry,
 252         .fh_to_parent = gfs2_fh_to_parent,
 253         .get_name = gfs2_get_name,
 254         .get_parent = gfs2_get_parent,
 255 };
 256