Revert "Revert "Revert "swap: allow swap readahead to be merged"""

This reverts commit f2184532be4ffae8436a4043746a52c8db3650bf.
Revert "Revert "Revert "mm: make swapin readahead skip over holes"""

This reverts commit 3060451ee6bbe3f6f042d36689f08b142f3d4fd9.
Revert "Revert "Revert page_io""

This reverts commit e94150d0737e8242dcf978bed790d0753f2515b9.
Revert "Revert "Revert "block: fix blk_queue_end_tag()"""

This reverts commit 43106f1c75eeb85aeca2f78d732136cd4fd10b8b.