[PATCH AUTOSEL 5.11 02/22] gfs2: Flag a withdraw if init_threads() fails

Sasha Levin
2021-04-05T16:04:22Z

From: Andrew Price <anprice@redhat.com>

[ Upstream commit 62dd0f98a0e5668424270b47a0c2e973795faba7 ]

Interrupting mount with ^C quickly enough can cause the kthread_run()
calls in gfs2's init_threads() to fail and the error path leads to a
deadlock on the s_umount rwsem. The abridged chain of events is:

[mount path]
get_tree_bdev()
sget_fc()
alloc_super()
down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING); [acquired]
gfs2_fill_super()
gfs2_make_fs_rw()
init_threads()
kthread_run()
( Interrupted )
[Error path]
gfs2_gl_hash_clear()
flush_workqueue(glock_workqueue)
wait_for_completion()

[workqueue context]
glock_work_func()
run_queue()
do_xmote()
freeze_go_sync()
freeze_super()
down_write(&sb->s_umount) [deadlock]

In freeze_go_sync() there is a gfs2_withdrawn() check that we can use to
make sure freeze_super() is not called in the error path, so add a
gfs2_withdraw_delayed() call when init_threads() fails.

Ref: https://bugzilla.kernel.org/show_bug.cgi?id=212231

Reported-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: Andrew Price <anprice@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/gfs2/super.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index 754ea2a137b4..34ca312457a6 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -169,8 +169,10 @@ int gfs2_make_fs_rw(struct gfs2_sbd *sdp)
int error;

error = init_threads(sdp);
- if (error)
+ if (error) {
+ gfs2_withdraw_delayed(sdp);
return error;
+ }

j_gl->gl_ops->go_inval(j_gl, DIO_METADATA);
if (gfs2_withdrawn(sdp)) {
--
2.30.2