On Thu, 24 Oct 2024 at 18:47, Hanna Czenczek <hreitz@xxxxxxxxxx> wrote:
> To be able to issue INIT (and GETATTR), we need to at least partially
> initialize the super_block structure, which is currently done via
> fuse_fill_super_common().
What exactly is needed to be initialized?
> @@ -1762,18 +1801,12 @@ int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
> sb->s_d_op = &fuse_dentry_operations;
>
> mutex_lock(&fuse_mutex);
> - err = -EINVAL;
> - if (ctx->fudptr && *ctx->fudptr)
> - goto err_unlock;
> -
> err = fuse_ctl_add_conn(fc);
> if (err)
> goto err_unlock;
>
> list_add_tail(&fc->entry, &fuse_conn_list);
> sb->s_root = root_dentry;
> - if (ctx->fudptr)
> - *ctx->fudptr = fud;
This is wrong, because we need the fuse_mutex protection for checking
and setting the private_data on the fuse device file.
If this split is needed (which I'm not sure) then fud allocation
should probably be moved to part2 instead of moving the *ctx->fudptr
setup to part1.
> @@ -1635,8 +1657,16 @@ static void virtio_kill_sb(struct super_block *sb)
> struct fuse_mount *fm = get_fuse_mount_super(sb);
> bool last;
>
> - /* If mount failed, we can still be called without any fc */
> - if (sb->s_root) {
> + /*
> + * Only destroy the connection after full initialization, i.e.
> + * once s_root is set (see commit d534d31d6a45d).
> + * One exception: For virtio-fs, we call INIT before s_root is
> + * set so we can determine the root node's mode. We must call
> + * DESTROY after INIT. So if an error occurs during that time
> + * window (specifically in fuse_make_root_inode()), we still
> + * need to call virtio_fs_conn_destroy() here.
> + */
> + if (sb->s_root || (fm->fc && fm->fc->initialized && !fm->submount)) {
How could fm->submount be set if sb->s_root isn't? Or sb->s_root set
and fc->initialized isn't?
Seems it would be sufficient to check fm->fc->initialized, no?
Thanks,
Miklos
