pstore: Adjust buffer size for compression for smaller registered buffers

When backends (ex: efivars) have smaller registered buffers, the
big_oops_buf is too big for them as number of repeated occurences
in the text captured will be less. What happens is that pstore takes
too big a bite from the dmesg log and then finds it cannot compress it
enough to meet the backend block size. Patch takes care of adjusting
the buffer size based on the registered buffer size. cmpr values have
been arrived after doing experiments with plain text for buffers of
size 1k - 4k (Smaller the buffer size repeated occurence will be less)
and with sample crash log for buffers ranging from 4k - 10k.

Reported-by: Seiji Aguchi <seiji.aguchi@hds.com>
Tested-by: Seiji Aguchi <seiji.aguchi@hds.com>
Signed-off-by: Aruna Balakrishnaiah <aruna@linux.vnet.ibm.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
pstore: Use zlib_inflateInit2 instead of zlib_inflateInit

Since zlib_deflateInit2() is used for specifying window bit during compression,
zlib_inflateInit2() is appropriate for decompression.

Reported-by: Seiji Aguchi <seiji.aguchi@hds.com>
Tested-by: Seiji Aguchi <seiji.aguchi@hds.com>
Signed-off-by: Aruna Balakrishnaiah <aruna@linux.vnet.ibm.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
pstore: Remove the messages related to compression failure

Remove the messages indicating compression failure as it will
add to the space during panic path.

Reported-by: Seiji Aguchi <seiji.aguchi@hds.com>
Tested-by: Seiji Aguchi <seiji.aguchi@hds.com>
Signed-off-by: Aruna Balakrishnaiah <aruna@linux.vnet.ibm.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Merge tag 'please-pull-pstore' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux

Pull pstore/compression fixes from Tony Luck:
 "Three pstore fixes related to compression:
   1) Better adjustment of size of compression buffer (was too big for
      EFIVARS backend resulting in compression failure
   2) Use zlib_inflateInit2 instead of zlib_inflateInit
   3) Don't print messages about compression failure.  They will waste
      space that may better be used to log console output leading to the
      crash"

* tag 'please-pull-pstore' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux:
  pstore: Remove the messages related to compression failure
  pstore: Use zlib_inflateInit2 instead of zlib_inflateInit
  pstore: Adjust buffer size for compression for smaller registered buffers