Re: [RFC PATCH] fs: introduce ST_HUGE flag and set it to tmpfs and hugetlbfs

From: Christoph Hellwig
Date: Thu Apr 19 2018 - 04:28:27 EST

On Wed, Apr 18, 2018 at 11:18:25AM -0700, Yang Shi wrote:
> Yes, thanks for the suggestion. I did think about it before I went with the
> new flag. Not like hugetlb, THP will *not* guarantee huge page is used all
> the time, it may fallback to regular 4K page or may get split. I'm not sure
> how the applications use f_bsize field, it might break existing applications
> and the value might be abused by applications to have counter optimization.
> So, IMHO, a new flag may sound safer.

But st_blksize isn't the block size, that is why I suggested it. It is
the preferred I/O size, and various file systems can report way
larger values than the block size already.