[0/2] Squashfs: handle missing pages decompressing into page cache

Message

Phillip Lougher June 11, 2022, 3:21 a.m. UTC

Hi all,

This patch-set enables Squashfs to handle missing pages when directly
decompressing datablocks into the page cache.

Previously if the full set of pages needed was not available, Squashfs
would have to fall back to using an intermediate buffer (the older
method), which is slower, involving a memcopy, and it introduces
contention on a shared buffer.

The first patch extends the "page actor" code to handle missing pages.

The second patch updates Squashfs_readpage_block() to use the new
functionality, and removes the code that falls back to using
an intermediate buffer.

This patch-set is independent of the readahead work, and it is
standalone.  It can be merged on its own.

But the readahead patch for efficiency also needs this patch-set.

Phillip

----------------------------------------------------------------
Phillip Lougher (2):
      Squashfs: extend "page actor" to handle missing pages
      Squashfs: don't use intermediate buffer if pages missing

 fs/squashfs/block.c        | 10 ++++--
 fs/squashfs/decompressor.h |  1 +
 fs/squashfs/file_direct.c  | 90 +++++++++++-----------------------------------
 fs/squashfs/lz4_wrapper.c  |  7 ++--
 fs/squashfs/lzo_wrapper.c  |  7 ++--
 fs/squashfs/page_actor.c   | 67 ++++++++++++++++++++++++++++------
 fs/squashfs/page_actor.h   | 17 +++++++--
 fs/squashfs/xz_wrapper.c   | 11 +++++-
 fs/squashfs/zlib_wrapper.c | 12 ++++++-
 fs/squashfs/zstd_wrapper.c | 12 ++++++-
 10 files changed, 142 insertions(+), 92 deletions(-)