lkml.org 
[lkml]   [2022]   [Nov]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: [PATCH v3 1/2] fscache,cachefiles: add prepare_ondemand_read() callback
    Date
    Jeff Layton <jlayton@kernel.org> 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.

    > 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.

    David

    \
     
     \ /
      Last update: 2022-11-16 14:43    [W:3.822 / U:0.300 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site