+static struct dentry *__snapfh_to_dentry(struct super_block *sb,
+ struct ceph_nfs_snapfh *sfh,
+ bool want_parent)
+{
+ struct ceph_mds_client *mdsc = ceph_sb_to_client(sb)->mdsc;
+ struct ceph_mds_request *req;
+ struct inode *inode;
+ struct ceph_vino vino;
+ int mask;
+ int err;
+ bool unlinked = false;
+
+ if (want_parent) {
+ vino.ino = sfh->parent_ino;
+ if (sfh->snapid == CEPH_SNAPDIR)
+ vino.snap = CEPH_NOSNAP;
+ else if (sfh->ino == sfh->parent_ino)
+ vino.snap = CEPH_SNAPDIR;
+ else
+ vino.snap = sfh->snapid;
+ } else {
+ vino.ino = sfh->ino;
+ vino.snap = sfh->snapid;
+ }
+ inode = ceph_find_inode(sb, vino);
+ if (inode)
+ return d_obtain_alias(inode);
+
+ req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPINO,
+ USE_ANY_MDS);
+ if (IS_ERR(req))
+ return ERR_CAST(req);
+
+ mask = CEPH_STAT_CAP_INODE;
+ if (ceph_security_xattr_wanted(d_inode(sb->s_root)))
+ mask |= CEPH_CAP_XATTR_SHARED;
+ req->r_args.lookupino.mask = cpu_to_le32(mask);
+ if (vino.snap < CEPH_NOSNAP) {
+ req->r_args.lookupino.snapid = cpu_to_le64(vino.snap);
+ if (!want_parent && sfh->ino != sfh->parent_ino) {
+ req->r_args.lookupino.parent =
+ cpu_to_le64(sfh->parent_ino);
+ req->r_args.lookupino.hash =
+ cpu_to_le32(sfh->hash);
+ }
+ }
+
+ req->r_ino1 = vino;
+ req->r_num_caps = 1;
+ err = ceph_mdsc_do_request(mdsc, NULL, req);
+ inode = req->r_target_inode;
+ if (inode) {
+ if (vino.snap == CEPH_SNAPDIR) {
+ if (inode->i_nlink == 0)
+ unlinked = true;
+ inode = ceph_get_snapdir(inode);
+ } else if (ceph_snap(inode) == vino.snap) {
+ ihold(inode);
+ } else {
+ /* mds does not support lookup snapped inode */
+ err = -EOPNOTSUPP;
+ inode = NULL;
+ }
+ }
+ ceph_mdsc_put_request(req);
+
+ if (want_parent) {
+ dout("snapfh_to_parent %llx.%llx\n err=%d\n",
+ vino.ino, vino.snap, err);
+ } else {
+ dout("snapfh_to_dentry %llx.%llx parent %llx hash %x err=%d",
+ vino.ino, vino.snap, sfh->parent_ino, sfh->hash, err);
+ }
+ if (!inode)
+ return ERR_PTR(-ESTALE);
+ /* see comments in ceph_get_parent() */
+ return unlinked ? d_obtain_root(inode) : d_obtain_alias(inode);
+}
+