Read/writes IOs should be page aligned as fuse server might need to copy data to another buffer otherwise in order to fulfill network or device storage requirements. Simple reproducer is with libfuse, example/passthrough* and opening a file with O_DIRECT - without this change writing to that file failed with -EINVAL if the underlying file system was using ext4 (for passthrough_hp the 'passthrough' feature has to be disabled). Given this needs server side changes as new feature flag is introduced. Disadvantage of aligned writes is that server side needs needs another splice syscall (when splice is used) to seek over the unaligned area - i.e. syscall and memory copy overhead. Signed-off-by: Bernd Schubert <bschubert@xxxxxxx> ---
