staging: erofs: differentiate unsupported on-disk format

For some specific fields, use EOPNOTSUPP instead of EIO
for values which look sane but aren't supported right now.
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NGao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190814103705.60698-2-gaoxiang25@huawei.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/erofs/inode.c

@@ -24,7 +24,7 @@ static int read_inode(struct inode *inode, void *data)
 		errln("unsupported data mapping %u of nid %llu",
 		      vi->datamode, vi->nid);
 		DBG_BUGON(1);
-		return -EIO;
+		return -EOPNOTSUPP;
 	}
 
 	if (__inode_version(advise) == EROFS_INODE_LAYOUT_V2) {
@@ -95,7 +95,7 @@ static int read_inode(struct inode *inode, void *data)
 		errln("unsupported on-disk inode version %u of nid %llu",
 		      __inode_version(advise), vi->nid);
 		DBG_BUGON(1);
-		return -EIO;
+		return -EOPNOTSUPP;
 	}
 
 	if (!nblks)

drivers/staging/erofs/zmap.c

@@ -178,7 +178,7 @@ static int vle_legacy_load_cluster_from_disk(struct z_erofs_maprecorder *m,
 		break;
 	default:
 		DBG_BUGON(1);
-		return -EIO;
+		return -EOPNOTSUPP;
 	}
 	m->type = type;
 	return 0;
@@ -362,7 +362,7 @@ static int vle_extent_lookback(struct z_erofs_maprecorder *m,
 		errln("unknown type %u at lcn %lu of nid %llu",
 		      m->type, lcn, vi->nid);
 		DBG_BUGON(1);
-		return -EIO;
+		return -EOPNOTSUPP;
 	}
 	return 0;
 }
@@ -436,7 +436,7 @@ int z_erofs_map_blocks_iter(struct inode *inode,
 	default:
 		errln("unknown type %u at offset %llu of nid %llu",
 		      m.type, ofs, vi->nid);
-		err = -EIO;
+		err = -EOPNOTSUPP;
 		goto unmap_out;
 	}