[FYI] tux3: Core changes
david at lang.hm
Wed May 20 11:01:12 PDT 2015
On Wed, 20 May 2015, Daniel Phillips wrote:
> On 05/20/2015 07:44 AM, Jan Kara wrote:
>> Yeah, that's what I meant. If you create a function which manipulates
>> page cache, you better make it work with other functions manipulating page
>> cache. Otherwise it's a landmine waiting to be tripped by some unsuspecting
>> developer. Sure you can document all the conditions under which the
>> function is safe to use but a function that has several paragraphs in front
>> of it explaning when it is safe to use isn't very good API...
> Violent agreement, of course. To put it in concrete terms, each of
> the page fork support functions must be examined and determined
> sane. They are:
> * cow_replace_page_cache
> * cow_delete_from_page_cache
> * cow_clone_page
> * page_cow_one
> * page_cow_file
> Would it be useful to drill down into those, starting from the top
> of the list?
It's a little more than determining that these 5 functions are sane, it's making
sure that if someone mixes the use of these functions with other existing
functions that the result is sane.
but it's probably a good starting point to look at each of these five functions
in detail and consider how they work and could interact badly with other things
touching the page cache.
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