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 (connectable && (*len < GFS2_LARGE_FH_SIZE)) {
  40                 *len = GFS2_LARGE_FH_SIZE;
  41                 return 255;
  42         } else if (*len < GFS2_SMALL_FH_SIZE) {
  43                 *len = GFS2_SMALL_FH_SIZE;
  44                 return 255;
  45         }
  46
  47         fh[0] = cpu_to_be32(ip->i_no_formal_ino >> 32);
  48         fh[1] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
  49         fh[2] = cpu_to_be32(ip->i_no_addr >> 32);
  50         fh[3] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
  51         *len = GFS2_SMALL_FH_SIZE;
  52
  53         if (!connectable || inode == sb->s_root->d_inode)
  54                 return *len;
  55
  56         spin_lock(&dentry->d_lock);
  57         inode = dentry->d_parent->d_inode;
  58         ip = GFS2_I(inode);
  59         igrab(inode);
  60         spin_unlock(&dentry->d_lock);
  61
  62         fh[4] = cpu_to_be32(ip->i_no_formal_ino >> 32);
  63         fh[5] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
  64         fh[6] = cpu_to_be32(ip->i_no_addr >> 32);
  65         fh[7] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
  66         *len = GFS2_LARGE_FH_SIZE;
  67
  68         iput(inode);
  69
  70         return *len;
  71 }
  72
  73 struct get_name_filldir {
  74         struct gfs2_inum_host inum;
  75         char *name;
  76 };
  77
  78 static int get_name_filldir(void *opaque, const char *name, int length,
  79                             loff_t offset, u64 inum, unsigned int type)
  80 {
  81         struct get_name_filldir *gnfd = opaque;
  82
  83         if (inum != gnfd->inum.no_addr)
  84                 return 0;
  85
  86         memcpy(gnfd->name, name, length);
  87         gnfd->name[length] = 0;
  88
  89         return 1;
  90 }
  91
  92 static int gfs2_get_name(struct dentry *parent, char *name,
  93                          struct dentry *child)
  94 {
  95         struct inode *dir = parent->d_inode;
  96         struct inode *inode = child->d_inode;
  97         struct gfs2_inode *dip, *ip;
  98         struct get_name_filldir gnfd;
  99         struct gfs2_holder gh;
 100         u64 offset = 0;
 101         int error;
 102         struct file_ra_state f_ra = { .start = 0 };
 103
 104         if (!dir)
 105                 return -EINVAL;
 106
 107         if (!S_ISDIR(dir->i_mode) || !inode)
 108                 return -EINVAL;
 109
 110         dip = GFS2_I(dir);
 111         ip = GFS2_I(inode);
 112
 113         *name = 0;
 114         gnfd.inum.no_addr = ip->i_no_addr;
 115         gnfd.inum.no_formal_ino = ip->i_no_formal_ino;
 116         gnfd.name = name;
 117
 118         error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED, 0, &gh);
 119         if (error)
 120                 return error;
 121
 122         error = gfs2_dir_read(dir, &offset, &gnfd, get_name_filldir, &f_ra);
 123
 124         gfs2_glock_dq_uninit(&gh);
 125
 126         if (!error && !*name)
 127                 error = -ENOENT;
 128
 129         return error;
 130 }
 131
 132 static struct dentry *gfs2_get_parent(struct dentry *child)
 133 {
 134         return d_obtain_alias(gfs2_lookupi(child->d_inode, &gfs2_qdotdot, 1));
 135 }
 136
 137 static struct dentry *gfs2_get_dentry(struct super_block *sb,
 138                                       struct gfs2_inum_host *inum)
 139 {
 140         struct gfs2_sbd *sdp = sb->s_fs_info;
 141         struct inode *inode;
 142
 143         inode = gfs2_ilookup(sb, inum->no_addr, 0);
 144         if (inode) {
 145                 if (GFS2_I(inode)->i_no_formal_ino != inum->no_formal_ino) {
 146                         iput(inode);
 147                         return ERR_PTR(-ESTALE);
 148                 }
 149                 goto out_inode;
 150         }
 151
 152         inode = gfs2_lookup_by_inum(sdp, inum->no_addr, &inum->no_formal_ino,
 153                                     GFS2_BLKST_DINODE);
 154         if (IS_ERR(inode))
 155                 return ERR_CAST(inode);
 156
 157 out_inode:
 158         return d_obtain_alias(inode);
 159 }
 160
 161 static struct dentry *gfs2_fh_to_dentry(struct super_block *sb, struct fid *fid,
 162                 int fh_len, int fh_type)
 163 {
 164         struct gfs2_inum_host this;
 165         __be32 *fh = (__force __be32 *)fid->raw;
 166
 167         switch (fh_type) {
 168         case GFS2_SMALL_FH_SIZE:
 169         case GFS2_LARGE_FH_SIZE:
 170         case GFS2_OLD_FH_SIZE:
 171                 this.no_formal_ino = ((u64)be32_to_cpu(fh[0])) << 32;
 172                 this.no_formal_ino |= be32_to_cpu(fh[1]);
 173                 this.no_addr = ((u64)be32_to_cpu(fh[2])) << 32;
 174                 this.no_addr |= be32_to_cpu(fh[3]);
 175                 return gfs2_get_dentry(sb, &this);
 176         default:
 177                 return NULL;
 178         }
 179 }
 180
 181 static struct dentry *gfs2_fh_to_parent(struct super_block *sb, struct fid *fid,
 182                 int fh_len, int fh_type)
 183 {
 184         struct gfs2_inum_host parent;
 185         __be32 *fh = (__force __be32 *)fid->raw;
 186
 187         switch (fh_type) {
 188         case GFS2_LARGE_FH_SIZE:
 189         case GFS2_OLD_FH_SIZE:
 190                 parent.no_formal_ino = ((u64)be32_to_cpu(fh[4])) << 32;
 191                 parent.no_formal_ino |= be32_to_cpu(fh[5]);
 192                 parent.no_addr = ((u64)be32_to_cpu(fh[6])) << 32;
 193                 parent.no_addr |= be32_to_cpu(fh[7]);
 194                 return gfs2_get_dentry(sb, &parent);
 195         default:
 196                 return NULL;
 197         }
 198 }
 199
 200 const struct export_operations gfs2_export_ops = {
 201         .encode_fh = gfs2_encode_fh,
 202         .fh_to_dentry = gfs2_fh_to_dentry,
 203         .fh_to_parent = gfs2_fh_to_parent,
 204         .get_name = gfs2_get_name,
 205         .get_parent = gfs2_get_parent,
 206 };
 207