fs/nfs/export.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2015, Primary Data, Inc. All rights reserved.
   4  *
   5  * Tao Peng <bergwolf@primarydata.com>
   6  */
   7 #include <linux/dcache.h>
   8 #include <linux/exportfs.h>
   9 #include <linux/nfs.h>
  10 #include <linux/nfs_fs.h>
  11
  12 #include "internal.h"
  13 #include "nfstrace.h"
  14
  15 #define NFSDBG_FACILITY         NFSDBG_VFS
  16
  17 enum {
  18         FILEID_HIGH_OFF = 0,    /* inode fileid high */
  19         FILEID_LOW_OFF,         /* inode fileid low */
  20         FILE_I_TYPE_OFF,        /* inode type */
  21         EMBED_FH_OFF            /* embeded server fh */
  22 };
  23
  24
  25 static struct nfs_fh *nfs_exp_embedfh(__u32 *p)
  26 {
  27         return (struct nfs_fh *)(p + EMBED_FH_OFF);
  28 }
  29
  30 /*
  31  * Let's break subtree checking for now... otherwise we'll have to embed parent fh
  32  * but there might not be enough space.
  33  */
  34 static int
  35 nfs_encode_fh(struct inode *inode, __u32 *p, int *max_len, struct inode *parent)
  36 {
  37         struct nfs_fh *server_fh = NFS_FH(inode);
  38         struct nfs_fh *clnt_fh = nfs_exp_embedfh(p);
  39         size_t fh_size = offsetof(struct nfs_fh, data) + server_fh->size;
  40         int len = EMBED_FH_OFF + XDR_QUADLEN(fh_size);
  41
  42         dprintk("%s: max fh len %d inode %p parent %p",
  43                 __func__, *max_len, inode, parent);
  44
  45         if (*max_len < len || IS_AUTOMOUNT(inode)) {
  46                 dprintk("%s: fh len %d too small, required %d\n",
  47                         __func__, *max_len, len);
  48                 *max_len = len;
  49                 return FILEID_INVALID;
  50         }
  51         if (IS_AUTOMOUNT(inode)) {
  52                 *max_len = FILEID_INVALID;
  53                 goto out;
  54         }
  55
  56         p[FILEID_HIGH_OFF] = NFS_FILEID(inode) >> 32;
  57         p[FILEID_LOW_OFF] = NFS_FILEID(inode);
  58         p[FILE_I_TYPE_OFF] = inode->i_mode & S_IFMT;
  59         p[len - 1] = 0; /* Padding */
  60         nfs_copy_fh(clnt_fh, server_fh);
  61         *max_len = len;
  62 out:
  63         dprintk("%s: result fh fileid %llu mode %u size %d\n",
  64                 __func__, NFS_FILEID(inode), inode->i_mode, *max_len);
  65         return *max_len;
  66 }
  67
  68 static struct dentry *
  69 nfs_fh_to_dentry(struct super_block *sb, struct fid *fid,
  70                  int fh_len, int fh_type)
  71 {
  72         struct nfs4_label *label = NULL;
  73         struct nfs_fattr *fattr = NULL;
  74         struct nfs_fh *server_fh = nfs_exp_embedfh(fid->raw);
  75         size_t fh_size = offsetof(struct nfs_fh, data) + server_fh->size;
  76         const struct nfs_rpc_ops *rpc_ops;
  77         struct dentry *dentry;
  78         struct inode *inode;
  79         int len = EMBED_FH_OFF + XDR_QUADLEN(fh_size);
  80         u32 *p = fid->raw;
  81         int ret;
  82
  83         /* NULL translates to ESTALE */
  84         if (fh_len < len || fh_type != len)
  85                 return NULL;
  86
  87         fattr = nfs_alloc_fattr();
  88         if (fattr == NULL) {
  89                 dentry = ERR_PTR(-ENOMEM);
  90                 goto out;
  91         }
  92
  93         fattr->fileid = ((u64)p[FILEID_HIGH_OFF] << 32) + p[FILEID_LOW_OFF];
  94         fattr->mode = p[FILE_I_TYPE_OFF];
  95         fattr->valid |= NFS_ATTR_FATTR_FILEID | NFS_ATTR_FATTR_TYPE;
  96
  97         dprintk("%s: fileid %llu mode %d\n", __func__, fattr->fileid, fattr->mode);
  98
  99         inode = nfs_ilookup(sb, fattr, server_fh);
 100         if (inode)
 101                 goto out_found;
 102
 103         label = nfs4_label_alloc(NFS_SB(sb), GFP_KERNEL);
 104         if (IS_ERR(label)) {
 105                 dentry = ERR_CAST(label);
 106                 goto out_free_fattr;
 107         }
 108
 109         rpc_ops = NFS_SB(sb)->nfs_client->rpc_ops;
 110         ret = rpc_ops->getattr(NFS_SB(sb), server_fh, fattr, label);
 111         if (ret) {
 112                 dprintk("%s: getattr failed %d\n", __func__, ret);
 113                 dentry = ERR_PTR(ret);
 114                 goto out_free_label;
 115         }
 116
 117         inode = nfs_fhget(sb, server_fh, fattr, label);
 118
 119 out_found:
 120         dentry = d_obtain_alias(inode);
 121
 122 out_free_label:
 123         nfs4_label_free(label);
 124 out_free_fattr:
 125         nfs_free_fattr(fattr);
 126 out:
 127         return dentry;
 128 }
 129
 130 static struct dentry *
 131 nfs_get_parent(struct dentry *dentry)
 132 {
 133         int ret;
 134         struct inode *inode = d_inode(dentry), *pinode;
 135         struct super_block *sb = inode->i_sb;
 136         struct nfs_server *server = NFS_SB(sb);
 137         struct nfs_fattr *fattr = NULL;
 138         struct nfs4_label *label = NULL;
 139         struct dentry *parent;
 140         struct nfs_rpc_ops const *ops = server->nfs_client->rpc_ops;
 141         struct nfs_fh fh;
 142
 143         if (!ops->lookupp)
 144                 return ERR_PTR(-EACCES);
 145
 146         fattr = nfs_alloc_fattr();
 147         if (fattr == NULL) {
 148                 parent = ERR_PTR(-ENOMEM);
 149                 goto out;
 150         }
 151
 152         label = nfs4_label_alloc(server, GFP_KERNEL);
 153         if (IS_ERR(label)) {
 154                 parent = ERR_CAST(label);
 155                 goto out_free_fattr;
 156         }
 157
 158         ret = ops->lookupp(inode, &fh, fattr, label);
 159         if (ret) {
 160                 parent = ERR_PTR(ret);
 161                 goto out_free_label;
 162         }
 163
 164         pinode = nfs_fhget(sb, &fh, fattr, label);
 165         parent = d_obtain_alias(pinode);
 166 out_free_label:
 167         nfs4_label_free(label);
 168 out_free_fattr:
 169         nfs_free_fattr(fattr);
 170 out:
 171         return parent;
 172 }
 173
 174 const struct export_operations nfs_export_ops = {
 175         .encode_fh = nfs_encode_fh,
 176         .fh_to_dentry = nfs_fh_to_dentry,
 177         .get_parent = nfs_get_parent,
 178 };