issue 39: make clear what "plog" is. solve name ambiguity.

plog_dev is split into plog_segs
plog_segs contains one or more plogs
plog contains metadata(plog_meta) and data(1-8 sectors)
and plog write is always atomic.

RENAMES:
plog_size -> plog_seg_size
and so on

Signed-off-by: Akira Hayakawa <ruby.wktk@gmail.com>
RENAME: origin_dev -> backing_dev

calling HDD backing device is more preferred
origin device is too general not for caching specifically.

my test scripts entirely use the word BACKING but the code uses
origin is inconsistent. this patch also fix this problem.

Signed-off-by: Akira Hayakawa <ruby.wktk@gmail.com>
Update the requirement of kernel config to run runtest.sh

Signed-off-by: Satoru Takeuchi <satoru.takeuchi@gmail.com>
Merge pull request #45 from satoru-takeuchi/satdoc

Update the requirement of kernel config to run runtest.sh
minor fix to README.md

Signed-off-by: Akira Hayakawa <ruby.wktk@gmail.com>
add config for local server

Signed-off-by: Akira Hayakawa <ruby.wktk@gmail.com>
implement read_segment_header() to reduce read amount in find_max_id()

- many modification of comments folded, too

Signed-off-by: Akira Hayakawa <ruby.wktk@gmail.com>
rename prepare.sh

- add install command to Makefile folded

Signed-off-by: Akira Hayakawa <ruby.wktk@gmail.com>
add init script installer

Signed-off-by: Akira Hayakawa <ruby.wktk@gmail.com>
modified README

Signed-off-by: Akira Hayakawa <ruby.wktk@gmail.com>
FIX: write header to writeboost and delete rc-installer.sh

don't write handmade installer but use insserv if you are using Debian

Signed-off-by: Akira Hayakawa <ruby.wktk@gmail.com>
add wb-installer.sh

Signed-off-by: Akira Hayakawa <ruby.wktk@gmail.com>
minor changes

Signed-off-by: Akira Hayakawa <ruby.wktk@gmail.com>
FIX: add plog_dev_desc in table

type=1 lacks its plog dev desc in the table output

Signed-off-by: Akira Hayakawa <ruby.wktk@gmail.com>
add line to mkdir mount point in init script

Signed-off-by: Akira Hayakawa <ruby.wktk@gmail.com>
add test HDD as cache in VM

Signed-off-by: Akira Hayakawa <ruby.wktk@gmail.com>