gfs2: Cease delete work during unmount

Add a check to delete_work_func() so that it quits when it finds that
the filesystem is deactivating.  This speeds up the delete workqueue
draining in gfs2_kill_sb().

In addition, make sure that iopen_go_callback() won't queue any new
delete work while the filesystem is deactivating.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

fs/gfs2/glock.c

@@ -1022,6 +1022,8 @@ static void delete_work_func(struct work_struct *work)
 		 * step entirely.
 		 */
 		if (gfs2_try_evict(gl)) {
+			if (test_bit(SDF_DEACTIVATING, &sdp->sd_flags))
+				goto out;
 			if (gfs2_queue_verify_evict(gl))
 				return;
 		}
@@ -1033,6 +1035,7 @@ static void delete_work_func(struct work_struct *work)
 					    GFS2_BLKST_UNLINKED);
 		if (IS_ERR(inode)) {
 			if (PTR_ERR(inode) == -EAGAIN &&
+			    !test_bit(SDF_DEACTIVATING, &sdp->sd_flags) &&
 			    gfs2_queue_verify_evict(gl))
 				return;
 		} else {

fs/gfs2/glops.c

@@ -648,7 +648,8 @@ static void iopen_go_callback(struct gfs2_glock *gl, bool remote)
 	struct gfs2_inode *ip = gl->gl_object;
 	struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
 
-	if (!remote || sb_rdonly(sdp->sd_vfs))
+	if (!remote || sb_rdonly(sdp->sd_vfs) ||
+	    test_bit(SDF_DEACTIVATING, &sdp->sd_flags))
 		return;
 
 	if (gl->gl_demote_state == LM_ST_UNLOCKED &&