On 11/16/22 9:41 PM, David Howells wrote: > Jeff Layton <jlayton@xxxxxxxxxx> wrote: > >>> +static enum netfs_io_source cachefiles_do_prepare_read(struct netfs_cache_resources *cres, >>> + loff_t *_start, size_t *_len, >>> + unsigned long *_flags, loff_t i_size) >> >> _start is never changed, so it should be passed by value instead of by >> pointer. > > Hmmm. The intention was that the start pointer should be able to be moved > backwards by the cache - but that's not necessary in ->prepare_read() and > ->expand_readahead() is provided for that now. So yes, the start pointer > shouldn't get changed at this point. Okay. > >> I'd also reverse the position of the arguments for _flags and i_size. >> Otherwise, the CPU/compiler have to shuffle things around more in >> cachefiles_prepare_ondemand_read before they call this. > > Better to pass the flags in and then ignore them. That way it can tail call, > or just call cachefiles_do_prepare_read() directly from erofs. If you're > going to have a wrapper, then you might be just as well create a > netfs_io_subrequest struct on the stack. I would prefer letting cachefiles_prepare_ondemand_read() pass flags in and then tail call cachefiles_do_prepare_read() directly. Many thanks for the suggestion. -- Thanks, Jingbo
