remove Xen tmem leftovers

[Christoph Hellwig]

Hi all,

since the remove of the Xen tmem driver in 2019, the cleancache hooks are
entirely unused, as are large parts of frontswap.  This series against
linux-next (with the folio changes included) removes cleancaches, and cuts
down frontswap to the bits actually used by zswap.

Diffstat:
 Documentation/vm/cleancache.rst        |  296 -------------------------------
 b/Documentation/vm/frontswap.rst       |   31 ---
 b/Documentation/vm/index.rst           |    1 
 b/MAINTAINERS                          |    7 
 b/arch/arm/configs/bcm2835_defconfig   |    1 
 b/arch/arm/configs/qcom_defconfig      |    1 
 b/arch/m68k/configs/amiga_defconfig    |    1 
 b/arch/m68k/configs/apollo_defconfig   |    1 
 b/arch/m68k/configs/atari_defconfig    |    1 
 b/arch/m68k/configs/bvme6000_defconfig |    1 
 b/arch/m68k/configs/hp300_defconfig    |    1 
 b/arch/m68k/configs/mac_defconfig      |    1 
 b/arch/m68k/configs/multi_defconfig    |    1 
 b/arch/m68k/configs/mvme147_defconfig  |    1 
 b/arch/m68k/configs/mvme16x_defconfig  |    1 
 b/arch/m68k/configs/q40_defconfig      |    1 
 b/arch/m68k/configs/sun3_defconfig     |    1 
 b/arch/m68k/configs/sun3x_defconfig    |    1 
 b/arch/s390/configs/debug_defconfig    |    1 
 b/arch/s390/configs/defconfig          |    1 
 b/block/bdev.c                         |    5 
 b/fs/btrfs/extent_io.c                 |   10 -
 b/fs/btrfs/super.c                     |    2 
 b/fs/ext4/readpage.c                   |    6 
 b/fs/ext4/super.c                      |    3 
 b/fs/f2fs/data.c                       |    7 
 b/fs/mpage.c                           |    7 
 b/fs/ntfs3/ntfs_fs.h                   |    1 
 b/fs/ocfs2/super.c                     |    2 
 b/fs/super.c                           |    3 
 b/include/linux/frontswap.h            |   35 ---
 b/include/linux/fs.h                   |    5 
 b/include/linux/shmem_fs.h             |    3 
 b/include/linux/swapfile.h             |    3 
 b/mm/Kconfig                           |   40 ----
 b/mm/Makefile                          |    1 
 b/mm/filemap.c                         |   11 -
 b/mm/frontswap.c                       |  259 +--------------------------
 b/mm/shmem.c                           |   33 ---
 b/mm/swapfile.c                        |   90 ++-------
 b/mm/truncate.c                        |   15 -
 b/mm/zswap.c                           |    8 
 include/linux/cleancache.h             |  124 ------------
 mm/cleancache.c                        |  315 ---------------------------------
 44 files changed, 65 insertions(+), 1274 deletions(-)