Revert "gfs2: fix a deadlock on withdraw-during-mount"

The current withdraw code duplicates the journal recovery code gfs2
already has for dealing with node failures, and it does so poorly.  That
code was added because when releasing a lockspace, we didn't have a way
to indicate that the lockspace needs recovery.  We now do have this
feature, so the current withdraw code can be removed almost entirely.
This is one of several steps towards that.

Reverts commit 865cc3e ("gfs2: fix a deadlock on
withdraw-during-mount").

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Author: Andreas Gruenbacher

fs/gfs2/glock.c

@@ -663,16 +663,6 @@ static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
 		clear_bit(GLF_LOCK, &gl->gl_flags);
 }
 
-static bool is_system_glock(struct gfs2_glock *gl)
-{
-	struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
-	struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
-
-	if (gl == m_ip->i_gl)
-		return true;
-	return false;
-}
-
 /**
  * do_xmote - Calls the DLM to change the state of a lock
  * @gl: The lock state
@@ -747,36 +737,29 @@ __acquires(&gl->gl_lockref.lock)
 	 * to see sd_log_error and withdraw, and in the meantime, requeue the
 	 * work for later.
 	 *
-	 * We make a special exception for some system glocks, such as the
-	 * system statfs inode glock, which needs to be granted before the
-	 * gfs2_quotad daemon can exit, and that exit needs to finish before
-	 * we can unmount the withdrawn file system.
-	 *
 	 * However, if we're just unlocking the lock (say, for unmount, when
 	 * gfs2_gl_hash_clear calls clear_glock) and recovery is complete
 	 * then it's okay to tell dlm to unlock it.
 	 */
 	if (glock_blocked_by_withdraw(gl) && target != LM_ST_UNLOCKED) {
-		if (!is_system_glock(gl)) {
-			request_demote(gl, LM_ST_UNLOCKED, 0, false);
-			/*
-			 * Ordinarily, we would call dlm and its callback would call
-			 * finish_xmote, which would call state_change() to the new state.
-			 * Since we withdrew, we won't call dlm, so call state_change
-			 * manually, but to the UNLOCKED state we desire.
-			 */
-			state_change(gl, LM_ST_UNLOCKED);
-			/*
-			 * We skip telling dlm to do the locking, so we won't get a
-			 * reply that would otherwise clear GLF_LOCK. So we clear it here.
-			 */
-			if (!test_bit(GLF_CANCELING, &gl->gl_flags))
-				clear_bit(GLF_LOCK, &gl->gl_flags);
-			clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
-			gl->gl_lockref.count++;
-			gfs2_glock_queue_work(gl, GL_GLOCK_DFT_HOLD);
-			return;
-		}
+		request_demote(gl, LM_ST_UNLOCKED, 0, false);
+		/*
+		 * Ordinarily, we would call dlm and its callback would call
+		 * finish_xmote, which would call state_change() to the new state.
+		 * Since we withdrew, we won't call dlm, so call state_change
+		 * manually, but to the UNLOCKED state we desire.
+		 */
+		state_change(gl, LM_ST_UNLOCKED);
+		/*
+		 * We skip telling dlm to do the locking, so we won't get a
+		 * reply that would otherwise clear GLF_LOCK. So we clear it here.
+		 */
+		if (!test_bit(GLF_CANCELING, &gl->gl_flags))
+			clear_bit(GLF_LOCK, &gl->gl_flags);
+		clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
+		gl->gl_lockref.count++;
+		gfs2_glock_queue_work(gl, GL_GLOCK_DFT_HOLD);
+		return;
 	}
 
 	if (ls->ls_ops->lm_lock) {