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

[Max Reitz]

On 07.05.20 11:56, Miklos Szeredi wrote:
> On Wed, May 6, 2020 at 5:37 PM Max Reitz <mreitz at redhat.com> wrote:
>>
>> From: Max Reitz <xanclic at xanclic.moe>

Oops.

>> 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).

I have to admit that I didn’t spend much thought on any of this, but
just went with what worked.  Since one of the functions in control.c
require the super block, I went with fuse_mount.

I suppose for fuse_ctl_add_conn() (for @name), we can simply use the
first fuse_mount’s device ID.

> BDI:  we need to call set_bdi_congested/clear_bdi_congested for *all*
> mounts of a connection.

OK, then one entry per fuse_conn will work.

But do we need to do the same in fuse_request_end() and
fuse_request_queue_background()?

>                          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.

Hm, sounds a bit cumbersome for the fuse_notify_* functions that don’t
directly call ilookup5().  But they always have a callee that does, so I
suppose I’ll just have to move that up to the caller.  That should work
then.

Thanks!

Max

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 488 bytes
Desc: OpenPGP digital signature
URL: <http://listman.redhat.com/archives/virtio-fs/attachments/20200507/2d9b4a7e/attachment.sig>