[Virtio-fs] [RFC 3/5] fuse: Split fuse_mount off of fuse_conn

[Miklos Szeredi]

On Wed, May 6, 2020 at 5:37 PM Max Reitz <mreitz at redhat.com> wrote:
>
> From: Max Reitz <xanclic at xanclic.moe>
>
> We want to allow submounts for the same fuse_conn, but with different
> superblocks so that each of the submounts has its own device ID.  To do
> so, we need to split all mount-specific information off of fuse_conn
> into a new fuse_mount structure, so that multiple mounts can share a
> single fuse_conn.

I have the following high level comments:

Control filesystem: each fuse_mount gets a new entry, but they are all
aliases.   I think we should just stick with just one entry for the
connection (and perhaps a symlink for each additional mount, but this
is of secondary importance).

BDI:  we need to call set_bdi_congested/clear_bdi_congested for *all*
mounts of a connection.  Might make sense to look into getting rid of
bdi congestion handling completely, but this is not something I have a
good insight into right now.

Notification: please create a fuse_ilookup() that takes fc and returns
(sb, inode) pair and call this instead ilookup5().   This way the loop
is moved to the place where it's actually necessary.

Thanks,
Miklos