[Cluster-devel] [syzbot] INFO: task hung in freeze_super (3)

[Tetsuo Handa]

Ping?

On 2023/01/04 22:47, Tetsuo Handa wrote:
> I suspect that cleanup is not done appropriately when gfs2_find_jhead() failed.
> Looking into gfs2_make_fs_rw(), I see there are two worrisome things.
> 
> One is that gfs2_make_fs_rw() returns an error without calling gfs2_consist(sdp) when
> gfs2_find_jhead() returned an error whereas gfs2_make_fs_rw() returns -EIO after calling
> gfs2_consist(sdp) when head.lh_flags does not contain GFS2_LOG_HEAD_UNMOUNT flag.
> 
> Since head.lh_flags is assigned by gfs2_find_jhead(), we might want to call gfs2_consist(sdp)
> when gfs2_find_jhead() returned an error. And actually
> 
> --- a/fs/gfs2/super.c
> +++ b/fs/gfs2/super.c
> @@ -138,7 +138,11 @@ int gfs2_make_fs_rw(struct gfs2_sbd *sdp)
>                 return -EIO;
> 
>         error = gfs2_find_jhead(sdp->sd_jdesc, &head, false);
> -       if (error || gfs2_withdrawn(sdp))
> +       if (error) {
> +               gfs2_consist(sdp);
> +               return error;
> +       }
> +       if (gfs2_withdrawn(sdp))
>                 return error;
> 
>         if (!(head.lh_flags & GFS2_LOG_HEAD_UNMOUNT)) {
> 
> avoids this deadlock. But I don't know when/how to use gfs2_withdraw().
> Please check if this change is appropriate.
> 
> The other worrisome thing is that gfs2_make_fs_rw() is returning 0 (and
> mount operation will continue) when gfs2_withdrawn() == true. Can the caller
> of gfs2_make_fs_rw() survive when callgfs2_make_fs_rw() returned 0 without
> processing
> 
>         /*  Initialize some head of the log stuff  */
>         sdp->sd_log_sequence = head.lh_sequence + 1;
>         gfs2_log_pointers_init(sdp, head.lh_blkno);
> 
> lines? Shouldn't the caller of gfs2_make_fs_rw() observe an error when
> gfs2_make_fs_rw() did not execute the
> 
> 	set_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags);
> 
> line due to gfs2_withdrawn() == true?
>