On Fri, Nov 18, 2016 at 12:02:46PM -0800, Eric Biggers wrote:
>
> This isn't validating s_log_block_size until after it's already been used in a
> shift, which means the code can have undefined behavior (shift by a value too
> large). Would it make sense to do something like the following instead?
> Similarly for the cluster size case.
Well, technically GCC is allowed to do *anything* with undefined
behavior, including forking and exec'ing a process to play larn or
rogue --- but that seems fairly unlikely. The main reason why I left
things the way it was is beause most of the time we want to print a
more user-friendly message about the blocksize, as opposed to
s_log_block_size.
> blocksize =
> BLOCK_SIZE << min_t(u32, le32_to_cpu(es->s_log_block_size), 20);
If I was going to do anything at all, it would probably be something like
blocksize =
BLOCK_SIZE << (le32_to_cpu(es->s_log_block_size) & 0x1F);
...on the theory that a boolean AND operation is going to be faster
and cheaper than a min_t.
- Ted
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