Re: [PATCH] fs: optimise generic_write_check_limits()

[Matthew Wilcox]

On Fri, Aug 06, 2021 at 12:22:10PM +0100, Pavel Begunkov wrote:
> Even though ->s_maxbytes is used by generic_write_check_limits() only in
> case of O_LARGEFILE, the value is loaded unconditionally, which is heavy
> and takes 4 indirect loads. Optimise it by not touching ->s_maxbytes,
> if it's not going to be used.

Is this "optimisation" actually worth anything?  Look at how
force_o_largefile() is used.  I would suggest that on the vast majority
of machines, O_LARGEFILE is always set.