Re: [PATCH 18/24] netfs: Speed up buffered reading

Simon Horman
2024-08-02T14:44:12Z

On Fri, Aug 02, 2024 at 03:18:02PM +0100, David Howells wrote:
> Simon Horman <horms@kernel.org> wrote:
>
> > If the code ever reaches this line, then slice will be used
> > uninitialised below.
>
> It can't actually happen (or, at least, it shouldn't). There are only three
> ways of obtaining data: downloading from the server
> (NETFS_DOWNLOAD_FROM_SERVER), reading from the cache (NETFS_READ_FROM_CACHE)
> and just clearing space (NETFS_FILL_WITH_ZEROES); each of those has its own
> if-statement that will set 'slice' or will switch the source to a different
> type that will set 'slice'.
>
> The problem is that the compiler doesn't know this.
>
> The check for NETFS_INVALID_READ is there just in case. Possibly:
>
> if (source == NETFS_INVALID_READ)
> break;
>
> could be replaced with a WARN_ON_ONCE() and an unconditional break.

Thanks, I think that should make the compiler happy without
significantly altering the flow or readability of the code.