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/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
  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 "super.h"
  25 #include "rgrp.h"
  26 #include "util.h"
  27
  28 #define GFS2_SMALL_FH_SIZE 4
  29 #define GFS2_LARGE_FH_SIZE 8
  30 #define GFS2_OLD_FH_SIZE 10
  31
  32 static int gfs2_encode_fh(struct dentry *dentry, __u32 *p, int *len,
  33                           int connectable)
  34 {
  35         __be32 *fh = (__force __be32 *)p;
  36         struct inode *inode = dentry->d_inode;
  37         struct super_block *sb = inode->i_sb;
  38         struct gfs2_inode *ip = GFS2_I(inode);
  39
  40         if (*len < GFS2_SMALL_FH_SIZE ||
  41             (connectable && *len < GFS2_LARGE_FH_SIZE))
  42                 return 255;
  43
  44         fh[0] = cpu_to_be32(ip->i_no_formal_ino >> 32);
  45         fh[1] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
  46         fh[2] = cpu_to_be32(ip->i_no_addr >> 32);
  47         fh[3] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
  48         *len = GFS2_SMALL_FH_SIZE;
  49
  50         if (!connectable || inode == sb->s_root->d_inode)
  51                 return *len;
  52
  53         spin_lock(&dentry->d_lock);
  54         inode = dentry->d_parent->d_inode;
  55         ip = GFS2_I(inode);
  56         igrab(inode);
  57         spin_unlock(&dentry->d_lock);
  58
  59         fh[4] = cpu_to_be32(ip->i_no_formal_ino >> 32);
  60         fh[5] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
  61         fh[6] = cpu_to_be32(ip->i_no_addr >> 32);
  62         fh[7] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
  63         *len = GFS2_LARGE_FH_SIZE;
  64
  65         iput(inode);
  66
  67         return *len;
  68 }
  69
  70 struct get_name_filldir {
  71         struct gfs2_inum_host inum;
  72         char *name;
  73 };
  74
  75 static int get_name_filldir(void *opaque, const char *name, int length,
  76                             loff_t offset, u64 inum, unsigned int type)
  77 {
  78         struct get_name_filldir *gnfd = opaque;
  79
  80         if (inum != gnfd->inum.no_addr)
  81                 return 0;
  82
  83         memcpy(gnfd->name, name, length);
  84         gnfd->name[length] = 0;
  85
  86         return 1;
  87 }
  88
  89 static int gfs2_get_name(struct dentry *parent, char *name,
  90                          struct dentry *child)
  91 {
  92         struct inode *dir = parent->d_inode;
  93         struct inode *inode = child->d_inode;
  94         struct gfs2_inode *dip, *ip;
  95         struct get_name_filldir gnfd;
  96         struct gfs2_holder gh;
  97         u64 offset = 0;
  98         int error;
  99
 100         if (!dir)
 101                 return -EINVAL;
 102
 103         if (!S_ISDIR(dir->i_mode) || !inode)
 104                 return -EINVAL;
 105
 106         dip = GFS2_I(dir);
 107         ip = GFS2_I(inode);
 108
 109         *name = 0;
 110         gnfd.inum.no_addr = ip->i_no_addr;
 111         gnfd.inum.no_formal_ino = ip->i_no_formal_ino;
 112         gnfd.name = name;
 113
 114         error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED, 0, &gh);
 115         if (error)
 116                 return error;
 117
 118         error = gfs2_dir_read(dir, &offset, &gnfd, get_name_filldir);
 119
 120         gfs2_glock_dq_uninit(&gh);
 121
 122         if (!error && !*name)
 123                 error = -ENOENT;
 124
 125         return error;
 126 }
 127
 128 static struct dentry *gfs2_get_parent(struct dentry *child)
 129 {
 130         struct qstr dotdot;
 131         struct dentry *dentry;
 132
 133         /*
 134          * XXX(hch): it would be a good idea to keep this around as a
 135          *           static variable.
 136          */
 137         gfs2_str2qstr(&dotdot, "..");
 138
 139         dentry = d_obtain_alias(gfs2_lookupi(child->d_inode, &dotdot, 1));
 140         if (!IS_ERR(dentry))
 141                 dentry->d_op = &gfs2_dops;
 142         return dentry;
 143 }
 144
 145 static struct dentry *gfs2_get_dentry(struct super_block *sb,
 146                                       struct gfs2_inum_host *inum)
 147 {
 148         struct gfs2_sbd *sdp = sb->s_fs_info;
 149         struct gfs2_holder i_gh;
 150         struct inode *inode;
 151         struct dentry *dentry;
 152         int error;
 153
 154         inode = gfs2_ilookup(sb, inum->no_addr);
 155         if (inode) {
 156                 if (GFS2_I(inode)->i_no_formal_ino != inum->no_formal_ino) {
 157                         iput(inode);
 158                         return ERR_PTR(-ESTALE);
 159                 }
 160                 goto out_inode;
 161         }
 162
 163         error = gfs2_glock_nq_num(sdp, inum->no_addr, &gfs2_inode_glops,
 164                                   LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
 165         if (error)
 166                 return ERR_PTR(error);
 167
 168         error = gfs2_check_blk_type(sdp, inum->no_addr, GFS2_BLKST_DINODE);
 169         if (error)
 170                 goto fail;
 171
 172         inode = gfs2_inode_lookup(sb, DT_UNKNOWN, inum->no_addr, 0);
 173         if (IS_ERR(inode)) {
 174                 error = PTR_ERR(inode);
 175                 goto fail;
 176         }
 177
 178         error = gfs2_inode_refresh(GFS2_I(inode));
 179         if (error) {
 180                 iput(inode);
 181                 goto fail;
 182         }
 183
 184         /* Pick up the works we bypass in gfs2_inode_lookup */
 185         if (inode->i_state & I_NEW)
 186                 gfs2_set_iop(inode);
 187
 188         if (GFS2_I(inode)->i_no_formal_ino != inum->no_formal_ino) {
 189                 iput(inode);
 190                 goto fail;
 191         }
 192
 193         error = -EIO;
 194         if (GFS2_I(inode)->i_diskflags & GFS2_DIF_SYSTEM) {
 195                 iput(inode);
 196                 goto fail;
 197         }
 198
 199         gfs2_glock_dq_uninit(&i_gh);
 200
 201 out_inode:
 202         dentry = d_obtain_alias(inode);
 203         if (!IS_ERR(dentry))
 204                 dentry->d_op = &gfs2_dops;
 205         return dentry;
 206 fail:
 207         gfs2_glock_dq_uninit(&i_gh);
 208         return ERR_PTR(error);
 209 }
 210
 211 static struct dentry *gfs2_fh_to_dentry(struct super_block *sb, struct fid *fid,
 212                 int fh_len, int fh_type)
 213 {
 214         struct gfs2_inum_host this;
 215         __be32 *fh = (__force __be32 *)fid->raw;
 216
 217         switch (fh_type) {
 218         case GFS2_SMALL_FH_SIZE:
 219         case GFS2_LARGE_FH_SIZE:
 220         case GFS2_OLD_FH_SIZE:
 221                 this.no_formal_ino = ((u64)be32_to_cpu(fh[0])) << 32;
 222                 this.no_formal_ino |= be32_to_cpu(fh[1]);
 223                 this.no_addr = ((u64)be32_to_cpu(fh[2])) << 32;
 224                 this.no_addr |= be32_to_cpu(fh[3]);
 225                 return gfs2_get_dentry(sb, &this);
 226         default:
 227                 return NULL;
 228         }
 229 }
 230
 231 static struct dentry *gfs2_fh_to_parent(struct super_block *sb, struct fid *fid,
 232                 int fh_len, int fh_type)
 233 {
 234         struct gfs2_inum_host parent;
 235         __be32 *fh = (__force __be32 *)fid->raw;
 236
 237         switch (fh_type) {
 238         case GFS2_LARGE_FH_SIZE:
 239         case GFS2_OLD_FH_SIZE:
 240                 parent.no_formal_ino = ((u64)be32_to_cpu(fh[4])) << 32;
 241                 parent.no_formal_ino |= be32_to_cpu(fh[5]);
 242                 parent.no_addr = ((u64)be32_to_cpu(fh[6])) << 32;
 243                 parent.no_addr |= be32_to_cpu(fh[7]);
 244                 return gfs2_get_dentry(sb, &parent);
 245         default:
 246                 return NULL;
 247         }
 248 }
 249
 250 const struct export_operations gfs2_export_ops = {
 251         .encode_fh = gfs2_encode_fh,
 252         .fh_to_dentry = gfs2_fh_to_dentry,
 253         .fh_to_parent = gfs2_fh_to_parent,
 254         .get_name = gfs2_get_name,
 255         .get_parent = gfs2_get_parent,
 256 };
 257