Commit 28c4d9bc authored by Andreas Gruenbacher's avatar Andreas Gruenbacher
Browse files

gfs2: Fix unlikely race in gdlm_put_lock 



In gdlm_put_lock(), there is a small window of time in which the
DFL_UNMOUNT flag has been set but the lockspace hasn't been released,
yet.  In that window, dlm may still call gdlm_ast() and gdlm_bast().
To prevent it from dereferencing freed glock objects, only free the
glock if the lockspace has actually been released.

Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: default avatarAndrew Price <anprice@redhat.com>
parent 6ab26555

fs/gfs2/lock_dlm.c

+5 −6
Original line number Diff line number Diff line
@@ -344,12 +344,6 @@ static void gdlm_put_lock(struct gfs2_glock *gl) 
	gfs2_sbstats_inc(gl, GFS2_LKS_DCOUNT);

	gfs2_update_request_times(gl);



	/* don't want to call dlm if we've unmounted the lock protocol */

	if (test_bit(DFL_UNMOUNT, &ls->ls_recover_flags)) {

		gfs2_glock_free(gl);

		return;

	}



	/*

	 * When the lockspace is released, all remaining glocks will be

	 * unlocked automatically.  This is more efficient than unlocking them
@@ -379,6 +373,11 @@ static void gdlm_put_lock(struct gfs2_glock *gl) 
		goto again;

	}



	if (error == -ENODEV) {

		gfs2_glock_free(gl);

		return;

	}



	if (error) {

		fs_err(sdp, "gdlm_unlock %x,%llx err=%d\n",

		       gl->gl_name.ln_type,