Re: [MAINTAINERS/KERNEL SUMMIT] Trust and maintenance of file systems

Theodore Ts'o
2023-09-18T20:51:08Z

On Mon, Sep 18, 2023 at 12:59:15PM -0700, Linus Torvalds wrote:
> On Mon, 18 Sept 2023 at 12:32, Jiri Kosina <jikos@kernel.org> wrote:
> >
> > I am afraid this is not reflecting reality.
> >
> > I am pretty sure that "give me that document on a USB stick, and I'll take
> > a look" leads to using things like libreoffice (or any other editor liked
> > by general public) to open the file directly on the FAT USB stick. And
> > that's pretty much guaranteed to use mmap().
>
> Ugh. I would have hoped that anybody will fall back to read/write -
> because we definitely have filesystems that don't support mmap.

Fortunately, I most of the "simple" file systems appear to support
mmap, via generic_file_mmap:

% git grep generic_file_mmap | grep ^fs | awk -F/ '{print $2}' | uniq | xargs echo

9p adfs affs afs bfs ecryptfs exfat ext2 fat fuse hfs hfsplus hostfs
hpfs jfs minix nfs ntfs ntfs3 omfs ramfs reiserfs smb sysv ubifs ufs
vboxsf

- Ted