Re: [PATCH] drop caches: skip tmpfs and ramfs

[Christoph Hellwig]

On Fri, Jun 24, 2022 at 06:21:21PM +0000, cgel.zte@xxxxxxxxx wrote:
> From: Ran Xiaokai <ran.xiaokai@xxxxxxxxxx>
> 
> All tmpfs and ramfs pages have PG_dirty bit set
> once they are allocated and added to the pagecache。So pages
> can not be freed from tmpfs or ramfs. So skip tmpfs and ramfs
> when drop caches.

Hard coding magic constants in VFS code is a bad idea.  If you have
numbers to justify this change (which should go into this commit log),
it can be properly solved by a flag on the super block,
file_system_type or even better bdi.