Further generalise the decompressors by adding a page handler
abstraction. This adds helpers to allow the decompressors
to access and process the output buffers in an implementation
independant manner.
This allows different types of output buffer to be passed
to the decompressors, with the implementation specific
aspects handled at decompression time, but without the
knowledge being held in the decompressor wrapper code.
This will allow the decompressors to handle Squashfs
cache buffers, and page cache pages.
This patch adds the abstraction and an implementation for
the caches.
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Reviewed-by: Minchan Kim <minchan@kernel.org>
The decompressor interface and code was written from
the point of view of single-threaded operation. In doing
so it mixed a lot of single-threaded implementation specific
aspects into the decompressor code and elsewhere which makes it
difficult to seamlessly support multiple different decompressor
implementations.
This patch does the following:
1. It removes compressor_options parsing from the decompressor
init() function. This allows the decompressor init() function
to be dynamically called to instantiate multiple decompressors,
without the compressor options needing to be read and parsed each
time.
2. It moves threading and all sleeping operations out of the
decompressors. In doing so, it makes the decompressors
non-blocking wrappers which only deal with interfacing with
the decompressor implementation.
3. It splits decompressor.[ch] into decompressor generic functions
in decompressor.[ch], and moves the single threaded
decompressor implementation into decompressor_single.c.
The result of this patch is Squashfs should now be able to
support multiple decompressors by adding new decompressor_xxx.c
files with specialised implementations of the functions in
decompressor_single.c
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Reviewed-by: Minchan Kim <minchan@kernel.org>
