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

David Howells
2024-08-02T14:18:22Z

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.

David