tree 87dabf362a851a94f1088374fb15af86d0c41977
parent 38840afd42c86ce39b70b286ee695ca821257666
author Adrien Schildknecht <adriens@google.com> 1476753752 -0700
committer Daniel Rosenberg <drosen@google.com> 1506027151 -0700

ANDROID: Squashfs: replace buffer_head with BIO

The 'll_rw_block' has been deprecated and BIO is now the basic container
for block I/O within the kernel.

Switching to BIO offers 2 advantages:
  1/ It removes synchronous wait for the up-to-date buffers: SquashFS
     now deals with decompressions/copies asynchronously.
     Implementing an asynchronous mechanism to read data is needed to
     efficiently implement .readpages().
  2/ Prior to this patch, merging the read requests entirely depends on
     the IO scheduler. SquashFS has more information than the IO
     scheduler about what could be merged. Moreover, merging the reads
     at the FS level means that we rely less on the IO scheduler.

Change-Id: I668812cc1e78e2f92497f9ebe0157cb8eec725ba
Signed-off-by: Adrien Schildknecht <adriens@google.com>