linux.git/fs/squashfs/decompressor_multi.c, branch v3.13

Squashfs: Check stream is not NULL in decompressor_multi.c

2013-11-20T03:59:20+00:00

Fix static checker complaint that stream is not checked in
squashfs_decompressor_destroy().

Reported-by: Dan Carpenter 
Signed-off-by: Phillip Lougher 
Reviewed-by: Minchan Kim

Squashfs: Generalise paging handling in the decompressors

2013-11-20T03:59:01+00:00

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 
Reviewed-by: Minchan Kim

squashfs: Enhance parallel I/O

2013-11-20T03:35:18+00:00

Now squashfs have used for only one stream buffer for decompression
so it hurts parallel read performance so this patch supports
multiple decompressor to enhance performance parallel I/O.

Four 1G file dd read on KVM machine which has 2 CPU and 4G memory.

dd if=test/test1.dat of=/dev/null &
dd if=test/test2.dat of=/dev/null &
dd if=test/test3.dat of=/dev/null &
dd if=test/test4.dat of=/dev/null &

old : 1m39s -> new : 9s

* From v1
  * Change comp_strm with decomp_strm - Phillip
  * Change/add comments - Phillip

Signed-off-by: Minchan Kim 
Signed-off-by: Phillip Lougher