From: Alexander Aring aahringo@redhat.com
commit 16e6281b6b22b0178eab95c6a82502d7b10f67b8 upstream.
Commit 0e539ca1bbbe ("gfs2: Fix NULL pointer dereference in gfs2_rgrp_dump") introduced additional locking in gfs2_rgrp_go_dump, which is also used for dumping resource group glocks via debugfs. However, on that code path, the glock spin lock is already taken in dump_glock, and taking it again in gfs2_glock2rgrp leads to deadlock. This can be reproduced with:
$ mkfs.gfs2 -O -p lock_nolock /dev/FOO $ mount /dev/FOO /mnt/foo $ touch /mnt/foo/bar $ cat /sys/kernel/debug/gfs2/FOO/glocks
Fix that by not taking the glock spin lock inside the go_dump callback.
Fixes: 0e539ca1bbbe ("gfs2: Fix NULL pointer dereference in gfs2_rgrp_dump") Signed-off-by: Alexander Aring aahringo@redhat.com Signed-off-by: Andreas Gruenbacher agruenba@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/gfs2/glops.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/gfs2/glops.c +++ b/fs/gfs2/glops.c @@ -230,7 +230,7 @@ static void rgrp_go_inval(struct gfs2_gl static void gfs2_rgrp_go_dump(struct seq_file *seq, struct gfs2_glock *gl, const char *fs_id_buf) { - struct gfs2_rgrpd *rgd = gfs2_glock2rgrp(gl); + struct gfs2_rgrpd *rgd = gl->gl_object;
if (rgd) gfs2_rgrp_dump(seq, rgd, fs_id_buf);