Re: [PATCH] mm/filemap: do not allocate cache pages beyond end of file at read

From: Linus Torvalds
Date: Tue Oct 29 2019 - 12:52:29 EST

On Tue, Oct 29, 2019 at 3:25 PM Konstantin Khlebnikov
<khlebnikov@xxxxxxxxxxxxxx> wrote:
> I think all network filesystems which synchronize metadata lazily should be
> marked. For example as "SB_VOLATILE". And vfs could handle them specially.

No need. The VFS layer doesn't call generic_file_buffered_read()
directly anyway. It's just a helper function for filesystems to use if
they want to.

They could (and should) make sure the inode size is sufficiently
up-to-date before calling it. And if they want something more
synchronous, they can do it themselves.

But NFS, for example, has open/close consistency, so the metadata
revalidation is at open() time, not at read time.