[PATCH 5.12 110/161] gfs2: fix scheduling while atomic bug in glocks

[Greg Kroah-Hartman]

From: Bob Peterson <rpeterso@xxxxxxxxxx>

commit 20265d9a67e40eafd39a8884658ca2e36f05985d upstream.

Before this patch, in the unlikely event that gfs2_glock_dq encountered
a withdraw, it would do a wait_on_bit to wait for its journal to be
recovered, but it never released the glock's spin_lock, which caused a
scheduling-while-atomic error.

This patch unlocks the lockref spin_lock before waiting for recovery.

Fixes: 601ef0d52e96 ("gfs2: Force withdraw to replay journals and wait for it to finish")
Cc: stable@xxxxxxxxxxxxxxx # v5.7+
Reported-by: Alexander Aring <aahringo@xxxxxxxxxx>
Signed-off-by: Bob Peterson <rpeterso@xxxxxxxxxx>
Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 fs/gfs2/glock.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -1465,9 +1465,11 @@ void gfs2_glock_dq(struct gfs2_holder *g
 	    glock_blocked_by_withdraw(gl) &&
 	    gh->gh_gl != sdp->sd_jinode_gl) {
 		sdp->sd_glock_dqs_held++;
+		spin_unlock(&gl->gl_lockref.lock);
 		might_sleep();
 		wait_on_bit(&sdp->sd_flags, SDF_WITHDRAW_RECOVERY,
 			    TASK_UNINTERRUPTIBLE);
+		spin_lock(&gl->gl_lockref.lock);
 	}
 	if (gh->gh_flags & GL_NOCACHE)
 		handle_callback(gl, LM_ST_UNLOCKED, 0, false);