Re: [PATCH 1/3] btrfs: ctree: Reduce one indent level for btrfs_search_slot()

[David Sterba <dsterba@suse.cz>]

On Tue, Sep 10, 2019 at 11:42:47AM +0300, Nikolay Borisov wrote:
> 
> 
> On 10.09.19 г. 11:31 ч., Qu Wenruo wrote:
> > 
> > 
> > On 2019/9/10 下午4:24, Nikolay Borisov wrote:
> >>
> >>
> >> On 10.09.19 г. 10:40 ч., Qu Wenruo wrote:
> >>> In btrfs_search_slot(), we something like:
> >>>
> >>> 	if (level != 0) {
> >>> 		/* Do search inside tree nodes*/
> >>> 	} else {
> >>> 		/* Do search inside tree leaves */
> >>> 		goto done;
> >>> 	}
> >>>
> >>> This caused extra indent for tree node search code.
> >>> Change it to something like:
> >>>
> >>> 	if (level == 0) {
> >>> 		/* Do search inside tree leaves */
> >>> 		goto done'
> >>> 	}
> >>> 	/* Do search inside tree nodes */
> >>>
> >>> So we have more space to maneuver our code, this is especially useful as
> >>> the tree nodes search code is more complex than the leaves search code.
> >>>
> >>> Signed-off-by: Qu Wenruo <wqu@suse.com>
> >>
> >> I actually thing this patch makes comprehending the function worse.
> > 
> > If the level == 0 lines is over 50 lines, maybe.
> > 
> > But it's just 22 lines.
> >> Because the else is now somewhat implicit. E.g. one has to pay careful
> >> attention to the contents inside the first if and especially the
> >> unconditional 'goto done' to be able to understand the code after the
> >> 'if' construct.
> > 
> > That's the same for the original code, you need to go a level upper to
> > see we're in level > 0 branch.
> 
> But that's explicit with the 'if'

Well, I don't see a strong reason for one or another. I see your point
about the explicit 'if/else' for a condition that has two exclusive
options.

I looked at the code with the patch applied and regarding readability,
the if (level == 0) block is short enough to be seen at once and is an
'take a shortcut here'. The indentation level reduction improvement
seems justified to me.