page swap in Linux kernel

Question

I know that Linux kernel has page cache to save recently used pages and blocks.

I understood that it helps to save time, because Linux doesn't need to get those blocks from a lower memory. When some block is missing in the cache, then Linux asks for it from lower level memory (by using some functions like submit_bio) and gets the block corresponding page.

I want to find the place in Linux kernel (3.10) where it checks for existence of the block in the page cache, and if it can't find this page, it brings the block from the block i/o layer.

I search for something like this in the code:

if( block's page exists in the cache )
    return this page
else 
    bring the page of the searched block and return it

Can anyone post a link to the place in the kernel where this decision made?

Answer 1

The best place to start looking is going to be in mm.h: http://lxr.linux.no/linux+v3.10.10/include/linux/mm.h

Then take a look at the mm directory, which has files like page_io.c: http://lxr.linux.no/linux+v3.10.10/mm/page_io.c

Keep in mind that any architecture specific stuff will likely be defined in the arch directory for the system you are looking at. For example, here is the x86 page table management code: http://lxr.linux.no/linux+v3.10.10/arch/x86/mm/pgtable.c

Good luck! Remember, you are likely not going to find a section of code as clean as the example code you gave.