readahead cleanups and interleaved readahead take 4

Andrew,

Here are some more readahead related cleanups and updates.

smaller file_ra_state:
[PATCH 01/10] readahead: compacting file_ra_state
[PATCH 02/10] readahead: mmap read-around simplification
[PATCH 03/10] readahead: combine file_ra_state.prev_index/prev_offset into prev_pos

Interleaved readahead:
[PATCH 04/10] radixtree: introduce radix_tree_scan_hole() [PATCH 05/10] readahead: basic support of interleaved reads

Readahead cleanups:
[PATCH 06/10] readahead: remove several readahead macros
[PATCH 07/10] readahead: remove the limit max_sectors_kb imposed on max_readahead_kb [PATCH 08/10] readahead: remove the local copy of ra in do_generic_mapping_read()

Filemap cleanups:
[PATCH 09/10] filemap: trivial code cleanups [PATCH 10/10] filemap: convert some unsigned long to pgoff_t

The diffstat is

 block/ll_rw_blk.c          |    9 ----
 fs/ext3/dir.c              |    2 -
 fs/ext4/dir.c              |    2 -
 fs/splice.c                |    2 -
 include/linux/fs.h         |   14 +++----
 include/linux/mm.h         |    2 -
 include/linux/pagemap.h    |   23 ++++++------
 include/linux/radix-tree.h |    2 +
 lib/radix-tree.c           |   36 +++++++++++++++++++
 mm/filemap.c               |   65 ++++++++++++++++-------------------
 mm/readahead.c             |   58 +++++++++++++++++--------------
 11 files changed, 122 insertions(+), 93 deletions(-)

Regards,
Fengguang Wu
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