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 inode *inode, __u32 *p, int *len,
  32                           struct inode *parent)
  33 {
  34         __be32 *fh = (__force __be32 *)p;
  35         struct super_block *sb = inode->i_sb;
  36         struct gfs2_inode *ip = GFS2_I(inode);
  37
  38         if (parent && (*len < GFS2_LARGE_FH_SIZE)) {
  39                 *len = GFS2_LARGE_FH_SIZE;
  40                 return FILEID_INVALID;
  41         } else if (*len < GFS2_SMALL_FH_SIZE) {
  42                 *len = GFS2_SMALL_FH_SIZE;
  43                 return FILEID_INVALID;
  44         }
  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 (!parent || inode == sb->s_root->d_inode)
  53                 return *len;
  54
  55         ip = GFS2_I(parent);
  56
  57         fh[4] = cpu_to_be32(ip->i_no_formal_ino >> 32);
  58         fh[5] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
  59         fh[6] = cpu_to_be32(ip->i_no_addr >> 32);
  60         fh[7] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
  61         *len = GFS2_LARGE_FH_SIZE;
  62
  63         return *len;
  64 }
  65
  66 struct get_name_filldir {
  67         struct dir_context ctx;
  68         struct gfs2_inum_host inum;
  69         char *name;
  70 };
  71
  72 static int get_name_filldir(void *opaque, const char *name, int length,
  73                             loff_t offset, u64 inum, unsigned int type)
  74 {
  75         struct get_name_filldir *gnfd = opaque;
  76
  77         if (inum != gnfd->inum.no_addr)
  78                 return 0;
  79
  80         memcpy(gnfd->name, name, length);
  81         gnfd->name[length] = 0;
  82
  83         return 1;
  84 }
  85
  86 static int gfs2_get_name(struct dentry *parent, char *name,
  87                          struct dentry *child)
  88 {
  89         struct inode *dir = parent->d_inode;
  90         struct inode *inode = child->d_inode;
  91         struct gfs2_inode *dip, *ip;
  92         struct get_name_filldir gnfd = {
  93                 .ctx.actor = get_name_filldir,
  94                 .name = name
  95         };
  96         struct gfs2_holder gh;
  97         int error;
  98         struct file_ra_state f_ra = { .start = 0 };
  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
 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, &gnfd.ctx, &f_ra);
 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         return d_obtain_alias(gfs2_lookupi(child->d_inode, &gfs2_qdotdot, 1));
 130 }
 131
 132 static struct dentry *gfs2_get_dentry(struct super_block *sb,
 133                                       struct gfs2_inum_host *inum)
 134 {
 135         struct gfs2_sbd *sdp = sb->s_fs_info;
 136         struct inode *inode;
 137
 138         inode = gfs2_ilookup(sb, inum->no_addr, 0);
 139         if (inode) {
 140                 if (GFS2_I(inode)->i_no_formal_ino != inum->no_formal_ino) {
 141                         iput(inode);
 142                         return ERR_PTR(-ESTALE);
 143                 }
 144                 goto out_inode;
 145         }
 146
 147         inode = gfs2_lookup_by_inum(sdp, inum->no_addr, &inum->no_formal_ino,
 148                                     GFS2_BLKST_DINODE);
 149         if (IS_ERR(inode))
 150                 return ERR_CAST(inode);
 151
 152 out_inode:
 153         return d_obtain_alias(inode);
 154 }
 155
 156 static struct dentry *gfs2_fh_to_dentry(struct super_block *sb, struct fid *fid,
 157                 int fh_len, int fh_type)
 158 {
 159         struct gfs2_inum_host this;
 160         __be32 *fh = (__force __be32 *)fid->raw;
 161
 162         switch (fh_type) {
 163         case GFS2_SMALL_FH_SIZE:
 164         case GFS2_LARGE_FH_SIZE:
 165         case GFS2_OLD_FH_SIZE:
 166                 if (fh_len < GFS2_SMALL_FH_SIZE)
 167                         return NULL;
 168                 this.no_formal_ino = ((u64)be32_to_cpu(fh[0])) << 32;
 169                 this.no_formal_ino |= be32_to_cpu(fh[1]);
 170                 this.no_addr = ((u64)be32_to_cpu(fh[2])) << 32;
 171                 this.no_addr |= be32_to_cpu(fh[3]);
 172                 return gfs2_get_dentry(sb, &this);
 173         default:
 174                 return NULL;
 175         }
 176 }
 177
 178 static struct dentry *gfs2_fh_to_parent(struct super_block *sb, struct fid *fid,
 179                 int fh_len, int fh_type)
 180 {
 181         struct gfs2_inum_host parent;
 182         __be32 *fh = (__force __be32 *)fid->raw;
 183
 184         switch (fh_type) {
 185         case GFS2_LARGE_FH_SIZE:
 186         case GFS2_OLD_FH_SIZE:
 187                 if (fh_len < GFS2_LARGE_FH_SIZE)
 188                         return NULL;
 189                 parent.no_formal_ino = ((u64)be32_to_cpu(fh[4])) << 32;
 190                 parent.no_formal_ino |= be32_to_cpu(fh[5]);
 191                 parent.no_addr = ((u64)be32_to_cpu(fh[6])) << 32;
 192                 parent.no_addr |= be32_to_cpu(fh[7]);
 193                 return gfs2_get_dentry(sb, &parent);
 194         default:
 195                 return NULL;
 196         }
 197 }
 198
 199 const struct export_operations gfs2_export_ops = {
 200         .encode_fh = gfs2_encode_fh,
 201         .fh_to_dentry = gfs2_fh_to_dentry,
 202         .fh_to_parent = gfs2_fh_to_parent,
 203         .get_name = gfs2_get_name,
 204         .get_parent = gfs2_get_parent,
 205 };
 206