btrfs: zero out left over bytes after processing compression streams

Don Bailey noticed that our page zeroing for compression at end-io time
isn't complete.  This reworks a patch from Linus to push the zeroing
into the zlib and lzo specific functions instead of trying to handle the
corners inside btrfs_decompress_buf2page

Signed-off-by: Chris Mason <[email protected]>
Reviewed-by: Josef Bacik <[email protected]>
Reported-by: Don A. Bailey <[email protected]>
cc: [email protected]
Signed-off-by: Linus Torvalds <[email protected]>
4 files changed