Re: [PATCH v4 19/19] fs: handle inode->i_version more efficiently

Jeff Layton
2018-01-08T13:46:31Z

On Mon, 2018-01-08 at 05:30 -0800, Matthew Wilcox wrote:
> On Fri, Dec 22, 2017 at 07:05:56AM -0500, Jeff Layton wrote:
> > + cur = inode_peek_iversion_raw(inode);
> > + for (;;) {
> > + /* If flag is clear then we needn't do anything */
> > + if (!force && !(cur & I_VERSION_QUERIED))
> > + return false;
> > + /* Since lowest bit is flag, add 2 to avoid it */
> > + new = (cur & ~I_VERSION_QUERIED) + I_VERSION_INCREMENT;
>
> Isn't this an extraordinarily complicated way of spelling:
>
> new = cur + 1;
>
> We know 'cur' has I_VERSION_QUERIED set, so clearing that bit and adding
> two is going to be the same as adding 1 ... right?
>

It would be, but if "force" is true, then I_VERSION_QUERIED may not be
set.
--
Jeff Layton <jlayton@kernel.org>