On Thu, 27 May 2021 15:24:40 +0200 Max Reitz <mreitz@xxxxxxxxxx> wrote: > On 25.05.21 17:02, Greg Kurz wrote: > > We recently fixed an infinite loop by setting the SB_BORN flag on > > submounts along with the write barrier needed by super_cache_count(). > > This is the job of vfs_get_tree() and FUSE shouldn't have to care > > about the barrier at all. > > > > Split out some code from fuse_dentry_automount() to a new dedicated > > fuse_get_tree_submount() handler for submounts and call vfs_get_tree(). > > > > The fs_private field of the filesystem context isn't used with > > submounts : hijack it to pass the FUSE inode of the mount point > > down to fuse_get_tree_submount(). > > What exactly do you mean by “isn’t used”? virtio_fs_init_fs_context() > still sets it (it is non-NULL in fuse_dentry_automount() after > fs_context_for_submount()). It does appear like it is never read, but > one thing that definitely would need to be done is for it to be freed > before putting mp_fi there. > Oops... yes it should. Thanks for the catch ! > So I think it may technically be fine to use this field, but then > virtio_fs_init_fs_context() shouldn’t set it for submounts (should be > discernible with fsc->purpose), and perhaps that should be a separate patch. > Yes, I'll do just that. > (Apart from that, this patch looks good to me, though.) > > Max > > > Finally, adapt virtiofs to use this. > > > > Signed-off-by: Greg Kurz <groug@xxxxxxxx> > > --- > > fs/fuse/dir.c | 58 +++++++-------------------------------------- > > fs/fuse/fuse_i.h | 6 +++++ > > fs/fuse/inode.c | 44 ++++++++++++++++++++++++++++++++++ > > fs/fuse/virtio_fs.c | 3 +++ > > 4 files changed, 62 insertions(+), 49 deletions(-) >
