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

From: Simon Horman <[email-masked]>
Date: Fri, 2 Aug 2024 15:44:05 +0100

On Fri, Aug 02, 2024 at 03:18:02PM +0100, David Howells wrote:
> Simon Horman <[email-masked]> 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.