+static struct dentry *shmem_get_parent(struct dentry *child)
+{
+ return ERR_PTR(-ESTALE);
+}
+
+static int shmem_match(struct inode *ino, void *vfh)
+{
+ __u32 *fh = vfh;
+ __u64 inum = fh[2];
+ inum = (inum << 32) | fh[1];
+ return ino->i_ino == inum && fh[0] == ino->i_generation;
+}
+
+static struct dentry *shmem_get_dentry(struct super_block *sb, void *vfh)
+{
+ struct dentry *de = NULL;
+ struct inode *inode;
+ __u32 *fh = vfh;
+ __u64 inum = fh[2];
+ inum = (inum << 32) | fh[1];
+
+ inode = ilookup5(sb, (unsigned long)(inum+fh[0]), shmem_match, vfh);
+ if (inode) {
+ de = d_find_alias(inode);
+ iput(inode);
+ }
+
+ return de? de: ERR_PTR(-ESTALE);
+}
+
+static struct dentry *shmem_decode_fh(struct super_block *sb, __u32 *fh,
+ int len, int type,
+ int (*acceptable)(void *context, struct dentry *de),
+ void *context)
+{
+ if (len < 3)
+ return ERR_PTR(-ESTALE);
+
+ return sb->s_export_op->find_exported_dentry(sb, fh, NULL, acceptable,
+ context);
+}
+
+static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
+ int connectable)
+{
+ struct inode *inode = dentry->d_inode;
+
+ if (*len < 3)
+ return 255;
+
+ if (hlist_unhashed(&inode->i_hash)) {
+ /* Unfortunately insert_inode_hash is not idempotent,
+ * so as we hash inodes here rather than at creation
+ * time, we need a lock to ensure we only try
+ * to do it once
+ */
+ static DEFINE_SPINLOCK(lock);
+ spin_lock(&lock);
+ if (hlist_unhashed(&inode->i_hash))
+ __insert_inode_hash(inode,
+ inode->i_ino + inode->i_generation);
+ spin_unlock(&lock);
+ }
+
+ fh[0] = inode->i_generation;
+ fh[1] = inode->i_ino;
+ fh[2] = ((__u64)inode->i_ino) >> 32;
+
+ *len = 3;
+ return 1;
+}
+
+static struct export_operations shmem_export_ops = {
+ .get_parent = shmem_get_parent,
+ .get_dentry = shmem_get_dentry,
+ .encode_fh = shmem_encode_fh,
+ .decode_fh = shmem_decode_fh,
+};
+